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snprintf() in C library

  • Difficulty Level : Basic
  • Last Updated : 18 Jul, 2021
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The snprintf() function formats and stores a series of characters and values in the array buffer. The snprintf() function with the addition of the n argument, which indicates the maximum number of characters (including at the end of null character) to be written to buffer. It is defined in <stdio.h> header file.

The snprintf() function is used to redirect the  output of  printf() function onto a buffer. 

The snprintf() also returns the number characters written onto the buffer, similar to the printf statement, which returns the number of characters that is printed in stdout.

Syntax : 

int snprintf(char *str, size_t size, const char *format, ...);

*str : is a buffer.
size : is the maximum number of bytes
(characters) that will be written to the buffer.
format : C string that contains a format
string that follows the same specifications as format in printf
... : the optional ( ā€¦) arguments 
are just the string formats like (ā€œ%dā€, myint) as seen in printf.



// C program to demonstrate snprintf()
#include <stdio.h>
int main()
    char buffer[50];
    char* s = "geeksforgeeks";
    // Counting the character and storing
    // in buffer using snprintf
    int j = snprintf(buffer, 6, "%s\n", s);
    // Print the string stored in buffer and
    // character count
    printf("string:\n%s\ncharacter count = %d\n",
                                     buffer, j);
    return 0;


character count = 14


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