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

Read More

 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

Read More

 ferror() function in C Programming language is used to identify the error in given c file. 

C program for ferror()

 

In this tutorial you will learn about how to use the ferror() function and programing syntax.

 Prototype :-  

 int ferror(FILE *filename);

Parameters :-

FILE *filename

C program for ferror() function

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

int main()
{
	FILE *fr;
	char str[100];

	if((f=fopen("help.txt","r"))==NULL){
		printf("Cannot open the file...");
		//file is not exist program is terminated
		exit(1);
	}

	// Check if here is some error in the file
	if(ferror(f))
		printf("print the Error to read the file\n");
	else	
		printf("No error\n");

	printf("File content is--\n");
	//print the strings until EOF is encountered
	while(!feof(fr)){
		fgets(str,100,fr);
		//print the string
		printf("%s",str);
	}

	//remember to close the opened file
	fclose(f);

	return 0;
}

Read More

System() function program in c

 In System library function in c use the command int system(const char *command) name or program name to the host environment and also executed command processor and returns the command after complete the task that is given in the c program.

 Parameters For System() function program in c :

Command:-  This string in c program containing the name of requested variable.  

 

Return the status of the command at the success and  returned is -1 on error.

 

Example:-

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

int main () {
   char command[50];

   strcpy( command, "-l" );
   system(command);

   return(0);
}

Example:-

This function list down the dir file with the help of c program

#include <stdio.h>
#include <string.h>

int main () {
   char command[50];

   strcpy( command, "dir" );
   system(command);

   return(0);
} 

system program in c

Read More

Example Program For Lab() Function In C Programming

 Lab() Function in c programming gives the absolute value of the integer and it return the absolute value of the long integer argument.

Showing program will tell how you can use the LAB function in c programming.

Example Program For  Lab() Function In C Programming

 

Parameters:-

Y − is a integral value. 

Return Value:-

This lab function returns the absolute value of y. 

LAB Function Program Example :-

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

int main () {
   long int e,d;

   e = labs(64887L);
   printf("Value for e = %ld\n", a);

   d = labs(-1003080L);
   printf("Value for d = %ld\n", b);
   
   return(0);
}

OUTPUT:-

Value for e = 64887
Value for d = 1003080

Read More

fput() program in C programming language

 fput() function in c programming is a file string function which is used to print a string to the file.

fput() function use two arguments pointer one of them is used for string and other one for file. 

A null terminated string pointed by str in to a file.A null character is not written into a given and at the time of success it returns the 0 and  EOF or -1.

fput() program in c language : -

#include<stdio.h>
#include<string.h>

int main()
{
    char str[50];
    FILE *fp;
    fp = fopen("yourfile2.txt", "w");

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

    printf("Testing with the help of fputs() function: \n\n");
    printf("To stop reading press Ctrl+Z in windows and Ctrl+D in Linux :");

    while( gets(str) != NULL )
    {
        fputs(str, fp);
    }

    fclose(fp);
    return 0;
}

Output :-

fput() program in C programming language

Read More

bsearch function program in c programming language

 bsearch function program in c language

bsearch function in c used to perform the search in the array and array will be sorted by the ascending order.

 A pointer will be used to sorted the array and the base point to the initial element for the given array and the key pointed to the object that containing the value that going to be sorted with the comparison function.

Return value for the bsearch program:-

If search goes successful, bsearch() returns a pointer to an identical element of the array. If two or more elements are equal, the element pointed to that it is not  specified.

If search goes unsuccessful finding the key, bsearch() returns NULL.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
 
#define NOSTRING 5
#define SIZE 26
 
int string_compare(void const *, void const *);
 
int main(void)
{
    int i;
    char strings[NOSTRING][SIZE];
    char search_str[SIZE];
    char *status;
 
    /* read strings from the user */
    printf("User, write in %d character strings...\n", NOSTRING);
    for (i= 0; i < NOSTRINGS; i++)
        fgets(strings[i], SIZE, stdin);
 
    printf("\n\n");
 
    /* display array of unsorted strings */
    printf("Before Sorting:\n");
    for (i = 0; i < NOSTRING; i++)
        fputs(strings[i], stdout);
 
    /* sort the array */
    qsort(strings, NOSTRING, SIZE, string_compare);
    printf("\n");
 
    /* array of sorted strings */
    printf("After Sorting:\n");
    for (i = 0; i < NOSTRING; i++)
        printf(strings[i], stdout);
 
    printf("\n\n");
 
    /* read the string to be searched for */
    printf("programer write about string you wish to search for...\n");
    fgets(search_str, SIZE, stdin);
    printf("\n");
 
    /* calling bsearch() to locate given string in the array */
    status = bsearch(search_str, strings, NOSTRINGS, SIZE, 
                       string_compare);
 
    /* verify if given value is found */
    assert(status != NULL);
    printf("your desired string is found!\n");
 
    return 0;
}
 
int string_compare(void const *str1, void const *str2)
{
    return strcmp((char *)str1, (char *)str2);
}

OUTPUT : -

 bsearch function program in c programming language

Read More