The **`snprintf()` function** redirects the output of the standard [`printf()`](https://www.educative.io/answers/how-to-use-printf-in-c) function to a buffer.

In C it is defined as:

> It is important to note that `snprintf()` appends a null character to the end of the resulting output. This null character is also counted towards the size of the string.

The function returns an integer, which is the number of characters that would have been written if the `buff_size` argument had been large enough. Therefore, the buffer is only considered to be completely written if the returned value is non-negative and less than `buff_size`.



This method is useful for avoiding the repetition of a formatted string. One can build a string once using `printf("%s", myBuffer)` instead of using`print("%d,%s,%f,%d", a,b,c,d)`, which is unnecessarily complex and cumbersome​.

The following code snippet demonstrates how to use ​the `snprintf()` function:

#include<stdio.h>

int main() {
    char buffer[100];
    int returnValue, buff_size = 38;
    char name[] = "Tony";
    int age = 21;

    returnValue = snprintf(buffer, buff_size, "My name is %s and I am %d years old", name, age);
    if (returnValue > 0 && returnValue < buff_size)
    {
        printf("%s\n", buffer);
        printf("Return value: %d", returnValue);
    }
    else
    {
        printf("Buffer was not written completely. Note the output below:\n");
        printf("%s\n", buffer);
        printf("Return value: %d", returnValue);
    }
}

What is the snprintf() function in C?

snprintf() redirects printf() output to a buffer, appending a null character, and returns the expected output length.