toupper() function in c with exmaple program

 toupper() function in c programming is used to convert lowercase alphabets to uppercase letters.

When a programmer passed a lowercase alphabet to toupper() function then it converts it to uppercase.

Or when a uppercase alphabet is passed then function returns same value.

Syntax for toupper() function in c :-

int toupper(int ch);

Example Program for toupper() in c :- 

Let's go with an simple s example program to convert lower case alphabet to uppercase using toupper() function.

#include <ctype.h> 

int main() 

{ 

    char ch; 

    // letter to convert to uppercase

    ch = 'a'; 

    printf("%c in uppercase is represented as %c", 

        ch, toupper(ch)); 

    return 0; 

} 

Note :- Remember toupper() in c only takes one character at a time.

So if you want to convert a hole word then use while loop for it

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line function in computer graphics

line function in c programming :-

Well line function in c computer graphics is used as it name says to draw a line from a point(x1,y1) to point(x2,y2) where (x2,y2) are end points to draw a line.

Here you can also check the c program to draw a line in computer graphics.

 C example program

 #include <graphics.h>
#include <conio.h>

main()
{
   int gd = DETECT, gm;

   initgraph(&gd, &gm, "C:\\TC\\BGI");

   line(100, 100, 200, 200);

   getch();
   closegraph();
   return 0;
}

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Example program for isxdigit() function in c

 The isxdigit() function in c programming checks whether a character is a hexadecimal digit character (0-9, a-f, A-F) or not.

Syntax for isxdigit in c :-

int isxdigit( int arg );

 isxdigit() Parameters

The isxdigit() in c takes a single character as it's parameter.

 C isxdigit() Return Value

 if passed argument is an hexadecimal character then isxdigit() return non-zero integer otherwise return 0.

Example program for C isxdigit() function

#include <ctype.h>
#include <stdio.h>

int main() {
   char c = '5';
   int result;

   // hexadecimal character is passed
   result = isxdigit(c); // result is non-zero
   printf("Result when %c is passed to isxdigit(): %d", c, isxdigit(c));

   c = 'M';

   // non-hexadecimal character is passed
   result = isxdigit(c); // result is 0

   printf("\nResult when %c is passed to isxdigit(): %d", c, isxdigit(c));

   return 0;
}

OUTPUT : - 

C isxdigit()

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Example program for isspace() in c

 The isspace() function in c programming used to check whether a character is a white-space character or not.

It return the non-zero integer if given argument to the isspace() in c is a white-space character, otherwise return 0.

Syntax For isspace() function in c: -

int isspace(int argument);

First check out the List of all white-space characters in C programming are:

Check white-space character

Example program for Check white-space character

#include <stdio.h>
#include <ctype.h>
int main()
{
    char c;
    int result;

    printf("Enter a character: ");
    scanf("%c", &c);
    
    result = isspace(c);

    if (result == 0)
    {
        printf("Not a white-space character.");
    }
    else
    {
        printf("White-space character.");
    }

    return 0;
}

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Example program for isprint() in c

 The isprint() function in c programming is used to check the given character is a printable character or not.

Printable characters in c programming are just the opposite of control characters and these type of characters checked using iscntrl() function in c.

Syntax for isprint() in c

int isprint( int arg );

for return value if the given characters passed to isprint() function in c is a printable character then it return non-zero integer otherwise return zero.

isprint() in c takes argument in the form of integer and returns.

Example for C isprint() function

 

#include <ctype.h>
#include <stdio.h>

int main()
{
    char c;

    c = 'Q';
    printf("Result when a printable character %c is passed to isprint(): %d", c, isprint(c));

    c = '\n';
    printf("\nResult when a control character %c is passed to isprint(): %d", c, isprint(c));

    return 0;
}

 OUTPUT : - 

C isprint() function in c

 

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Example program for isgraph in c

 The isgraph() function in c use to checks that given character is a graphic character or not.

What is graphic character:- Characters which have graphical representation are call as graphic characters. 

isgraph in c return the non zero integer if passed argument is an 
graphic character otherwise returns 0.

Syntax for isgraph in c 

int isgraph(int argument);

 Example program to Check graphic character with help of isgraph in c

 

#include <stdio.h>
#include <ctype.h>
int main()
{
    char c;
    int result;

    c = ' ';
    result = isgraph(c);
    printf("When %c is passed to isgraph() = %d\n", c, result);

    c = '\n';
    result = isgraph(c);
    printf("When %c is passed to isgraph() = %d\n", c, result);

    c = '9';
    result = isgraph(c);
    printf("When %c is passed to isgraph() = %d\n", c, result);  

 OUTPUT : -

When   is passed to isgraph() = 0
When 
 is passed to isgraph() = 0
When 9 is passed to isgraph() = 1

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Example program for iscntrl() function in c

•   iscntrl() function in c Used to check if the given character is a control character or not.

• Characters that are not print on the screen are known as control characters for exam newline.

•  If a character passed by iscntrl() function is a  control character then it  return non zero integer value otherwise return 0. 

•   iscntrl() C is define in ctype.h header file.

• this function  takes a single argument and returns an integer.
  

Syntax for iscntrl() in c :-

int iscntrl(int argument);

Example program for iscntrl() in c : -

 

#include <stdio.h>
#include <ctype.h>

int main()
{
    char c;
    int result;

    c = 'Q';
    result = iscntrl(c);
    printf("When %c is passed to iscntrl() = %d\n", c, result);

    c = '\n';
    result = iscntrl(c);
    printf("When %c is passed to iscntrl() = %d", c, result);

    return 0;
}

 OUTPUT : -

When Q is passed to iscntrl() = 0
When 
 is passed to iscntrl() = 1

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Example program for islower() function in c

 The islower() function in c checks  that the given character is lowercase alphabet (a-z) or not.

Syntax :- 

int islower( int arg );

 islower() function takes a single argument in the form of  integer and return the value of integer type.

Return Value islower() function in c : -

• Non-zero number (x > 0)  it means given Argument is a lowercase alphabet.

• Zero (0) then given Argument is not a lowercase alphabet.
  

Example for C islower() function in c

#include <stdio.h>
#include <ctype.h>

int main()
{
    char c;

    c='t';
    printf("Return value when %c is passed to islower(): %d", c, islower(c));

    c='D';
    printf("\nReturn value when %c is passed to islower(): %d", c, islower(c));

    return 0;
}

Output

Return value when t is passed to islower(): 2 Return value when D is passed to is islower(): 0

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Example Program for isdigit() in c - Function in c

 isdigit() function in C programming use to checks whether a character is numeric character (0-9) or not.

 Prototype of isdigit() Function in C

int isdigit( int arg );

• isdigit() function in c programming take a single argument which is an integer and return type int.
• Given character is converted to its ASCII value in isdigit() Function
• It is defined in <ctype.h> header file in c.

Return value for C isdigit()

 isdigit() Return value in c

Example Program for isdigit() function in c

#include <stdio.h>
#include <ctype.h>

int main()
{
    char c;
    c='5';
    printf("Result when numeric character is passed: %d", isdigit(c));

    c='+';
    printf("\nResult when non-numeric character is passed: %d", isdigit(c));

    return 0;
}

OUTPUT : - 

Result when numeric character is passed: 1
Result when non-numeric character is passed: 0

 

 

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Example program for isalpha in c - Function In C

 The isalpha() function in  programming is used to check whether a character is an alphabet or not.

If a character is prove that it is an is an alphabet with the help of isalpha() function in c then it return non zero integer otherwise it gives zero. 

This function is define in the <ctype.h> header file in c.

C isalpha() Prototype

int isalpha(int argument);

isalpha() function in c takes a single argument in the form of integer and give an integer value.

Return Value For isalpha() in C

Return Value For isalpha()

Example Program: C isalpha() function

#include <stdio.h>
#include <ctype.h>
int main()
{
    char c;
    c = 'Q';
    printf("\nResult when uppercase alphabet is passed: %d", isalpha(c));

    c = 'q';
    printf("\nResult when lowercase alphabet is passed: %d", isalpha(c));

    c='+';
    printf("\nResult when non-alphabetic character is passed: %d", isalpha(c));

    return 0;
}

OUTPUT : - 

Result when uppercase alphabet is passed: 1
Result when lowercase alphabet is passed: 2
Result when non-alphabetic character is passed: 0 

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Program for perror function in c - library function

 perror is a c library function in c this function is used to print a descriptive error message in c.

Program for perror function

 

Syntax:-

void perror(const char *str)

• str in c contain a custom message that is printed before the error message itself.
• perror function in c doesn't return any value

Example Program for perror function in c

#include <stdio.h>

int main () {
   FILE *f;

 
   /* first rename the file */
   rename("file.txt", "updatefile.txt");

   /* now let's open same file */
   f = fopen("file.txt", "r");
   if( fp == NULL ) {
      perror("Error: ");
      return(-1);
   }
   fclose(fp);
      
   return(0);
}

Output

Error: : No such file or directory

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Example program for tmpfile() function in c programming

•  tmpfile() function in c programming is used to created the temporary file in program and this temporary file will be deleted after  termination of c program.
  

• wb+ mode is used to opens file in binary update 

Example program for tmpfile() function in c programming

 

Syntax :- 

FILE *tmpfile(void) 

• this function return the file after creating the temporary file.

Program example for tmpfile() function in c

#include <stdio.h>
int main() 
{ 
    char str[] = "Hello function in c"; 
    int i = 0; 
  
    FILE* tmp = tmpfile(); 
    if (tmp == NULL) 
    { 
        puts("Unable to create temp file"); 
        return 0; 
    } 
  
    puts("Temporary file is created\n"); 
    while (str[i] != '\0') 
    { 
        fputc(str[i], tmp); 
        i++; 
    } 
  
    // rewind() function sets the file pointer 
    // at the beginning of the stream. 
    rewind(tmp); 
  
    while (!feof(tmp)) 
        putchar(fgetc(tmp)); 
} 

OUTPUT : -

Temporary file is created
Hello function in c

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Example Program for setbuf Function in c

 setbuf() function in c programming is used to define how stream should be buffered and this function should be call when a file associated with the stream and a already open file but any input or output shouldn't take place.

Example Program for setbuf Function in c

 

Parameter for setbuf() function program

steam is an pointer in this program and a allocated buffer is used.

This function doesn't return any thing.

Example program for setbuf() :-

#include <stdio.h>

int main () {
   char buf[BUFSIZ];

   setbuf(stdout, buf);
   puts("This is functioinc.in");

   fflush(stdout);
   return(0);
}

OUTPUT

This is functioinc.in

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Example program for ftell function in c

 ftell() function in c is used to get the total size of file after move the file pointer to the end of the file and it return the current position in long type.

File can have more than 32767 bytes of data

Syntax : -

long int ftell(FILE *stream)

Let's Check out the Program for ftell() function in c programming.

 

#include <stdio.h>
#include <conio.h>
void main () {
   FILE *f;
   int len;
   f = fopen("one.txt", "r");
   if(f == NULL) {
      perror(“Error opening file”);
      return(-1);
   }
   fseek(f, 0, SEEK_END);
   len = ftell(f);
   fclose(f);
   printf("Size of file: %d bytes", len);
   getch();
}

OUTPUT For ftell() function program

ftell() in c

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Example program for fsetpos() function in C programming

 In c handling, fsetpos() function will be used to set the position of input file with the help of fsetpos() access that point.

If you use to fix the file indicator position at any time in the given file then we need to use the fsetpos() function.

 Return Value :- fsetpos() function return zero at the time of success or non zero at failure. 

Example program for fsetpos() function in C programming

 

Example program for fsetpos() function

#include <stdio.h>
#include <stdlib.h>

int main(){
	
	FILE *f;
	
	char ch[100];
	
	fpos_t pos;

	
	f=fopen("functioninc.txt","w+");
	
	fgetpos(f,&pos);
	printf("Enter any five strings\n");
	for(int i=0;i<4;i++){
		
		scanf("%[^\n]",&ch);
		//write back to the file
		fputs(ch,f);
		
		fputs("\n",f);
		
		fflush(stdin);
	}
	//take the strings from the users
	scanf("%[^\n]",&ch);
	fputs(ch,f);
	
	fsetpos(f,&pos);
	printf("\n...............print the strings..............\n\n");
	while(!feof(f)){
		
		fgets(ch,100,f);
		
		printf("%s",ch);
	}

	//close the file
	fclose(f);

	return 0;
}<4 0="" 100="" a="" after="" and="" array="" back="" buffer="" ch="" character="" clear="" close="" don="" entry.otherwise="" entry="" every="" except="" f="" fclose="" feof="" fflush="" fgets="" file="" first="" for="" fputs="" from="" fsetpos="" i="" if="" in="" indicator="" initial="" is="" last="" line="" n...............print="" n="" new="" of="" or="" pos="" position="" pre="" print="" printf="" return="" s="" scanf="" set="" space="" stdin="" stream="" string="" strings..............="" strings="" t="" take="" takes="" taking="" the="" then="" this="" time="" to="" twice="" users="" waiting="" we="" while="" white="" write="">

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Example Program for FSEEK() function in c programming

 fseek() function in c programming is used to write data into desired file with the help of pointer which help to find the location into the given file.

Example Program for FSEEK() function in c programming

 

Syntax :-

int fseek(FILE *stream, long int offset, int whence)  

There are three constants are used in fseeks() function in c  SEEK_SET, SEEK_CUR and SEEK_END

 #include <stdio.h>
void main(){  
   FILE *fp;  
  
   fp = fopen("myfile.txt","w+");  
   fputs("This is functioinc", fp);  
    
   fseek( fp, 7, SEEK_SET );  
   fputs("Adam stiffman", fp);  
   fclose(fp);  
} 

Now let see the Example Program for FSEEK() function in c

#include <stdio.h>
int main ()
{
   FILE *f;
   char data[60];
   fp = fopen ("test.c","w");
   fputs("functioinc.in is a programming tutorial website", f);
   fgets ( data, 60, fp );
   printf(Before fseek - %s", data); 
 
   // To set file pointet to 21th byte/character into the file
   fseek(f, 21, SEEK_SET);
   fflush(data);
   fgets ( data, 60, fp );
   printf("After SEEK_SET to 21 - %s", data);
 
   // To find backward 10 bytes 
   fseek(f, -10, SEEK_CUR);
   fflush(data);
   fgets ( data, 60, fp );
   printf("After SEEK_CUR to -10 - %s", data);
 
   // To find 7th byte before the end of file
   fseek(f, -7, SEEK_END); 
   fflush(data);
   fgets ( data, 60, f );
   printf("After SEEK_END to -7 - %s", data);
 
   // now set file pointer to the start of the file
   fseek(f, 0, SEEK_SET); 
 
   fclose(f);
   return 0;
}

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Example program for fprintf() function in c

 

•  The fprintf() function in c is used to write the formatted data into the file.

• This didn't print the data on the console.
  

• All the arguments of function fprintf() is same as the printf() but fprintf() has an extra arguments which is pointer that is used to find the location where the formatted data is written in a file.

 Return value for fprintf() function:- This function return the total number of characters written to the file.

On the other hand it return the EOF when any error occurred. 

Program for fprintf() function in c : -  

#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *f;
    char Name[50];
    int roll_num, chars, i, n;
    float mark;

    fp = fopen("records.txt", "w");

    if(f == NULL)
    {
        printf("Error opening file\n");
        exit(1);
    }

    printf("Testing fprintf() function: \n\n");

    printf("Enter the number of records you want to enter: ");
    scanf("%d", &n);

    for(i = 0; i < n; i++)
    {
        fflush(stdin);
        printf("\nEnter the details of student %d \n\n", i +1);

        printf("Enter name of the student: ");
        gets(name);

        printf("Enter roll no: ");
        scanf("%d", &roll_num);

        printf("Enter marks: ");
        scanf("%f", &mark);

        chars = fprintf(f, "Name: %s\t\tRoll no: %d\t\tMarks: %.2f\n",
            Name, roll_num, mark);
       printf("\n%d characters successfully written to the file\n\n", chars);
    }

    fclose(f);
    return 0;
}

 Output fprintf() program: -

 

Example Program For fprintf() function in c

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List of function program in c programming language

 Well as all of you can see in previous tutorial of function in c programming we try to cover all in-build function in c not just only c but also other programming language like python, javascript, SQL, and other languages.

List of function program in c programming language

 

 

In this tutorial you can find all the function program in c and also learn about HOW TO USE IN-BUILD FUNCTION IN C with program example with explanation for these programs.

Check out our list of function program in c 

• C program to seek out the length of the string

•  Use of strlen() function in c programming 

• strcmp() C Program and strncmp() function in c

• Example of strcpy Program In C 

• C program example for strchr function in c 

• Strcspn function in c

• Example for bsearch function program in c

• fput() program in C

• Example Program For Lab() Function

• Example program for System() function in c

• C program for ferror()

• Example program for fscanf  function

• Learn to use the fflush in c

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How to use the fflush in c programming with example

 fflush() function in c programming is use to  flushes the contents of output to given file.

Understand the fflush function:-

To discuses the common issue due to the output buffering after the execute the c program.

#include <stdio.h>
 
int main() {
    fprintf(stdout, "This is to stdout. ");
    fprintf(stderr, "This is to stderr. ");
    fprintf(stdout, "This is also to stdout. ");
}

Out for this code snippet comes in different order.

fflush function program in c

The reason behind for this random order is buffered of any file in computer.

Well by default stdout is newline-buffered and on the other hand stderr is unbuffered. 

For stdout the content will be stored inside the temporary buffer so the output will be displayed when counters a newline or end of the file.

 On the other hand  stderr is not buffered the out will be written immediately.

That's why the stderr will be displayed first in upper program.

But if you want to displayed the standout output first the you have to flush the output with the fflush program in c.

#include <stdio.h>
 
int main() {
    fprintf(stdout, "This is to stdout. ");
    // output stream immediately
    fflush(stdout);
    fprintf(stderr, "This is to stderr. ");
   
    fprintf(stdout, "This is also to stdout. ");
    // output stream immediately
    fflush(stdout);
}

Output Of fflush program in c

Output

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 fscanf() function in c programming is used to read input from a file. 

Well this function works same as the scanf() function in c programming but instead of read the given input in c program fscanf() function read the data from file.

Most of the arguments of fscanf() function in c are same as scanf() function.

•  Return Value For fscanf() function program in c:-

This function return the number of value and complete the read operation or return the end of file EOF and -1 on error occurred.

 

Example program for fscanf() function in c

#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *f;
    char Name[50];
    int roll_num, chars;
    float mark;

    fp = fopen("records.txt", "r");

    if(f == NULL)
    {
        printf("Error opening file\n");
        exit(1);
    }

    printf("Testing fscanf() function: \n\n");
    printf("Name:\t\tRoll\t\tMarks\n");

    while( fscanf(f, "Name: %s\t\tRoll num: %d\t\tMarks: %f\n"
                    , Name, &roll_num, &mark) != EOF )
    {
        printf("%s\t\t%d\t\t%.2f\n", name, roll_no ,marks);
    }

    fclose(f);
    return 0;
}

Output of c program

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