snprintf functionThe snprintf function in C is defined in the stdio.h standard library and is used to write a series of characters into a character array. The main difference between snprintf and sprintf is that the former takes an argument that specifies the number of characters to write to the character array, whereas the latter does not take such an argument.
The structure of the snprintf function is a follows:
int snprintf(char * str, size_t size, const char * format, ...);
Where:
str is the pointer to the character array to which the characters are supposed to be written tosize is an integer which denotes the number of characters to writeformat is a format string as defined for the printf function... denotes optional parameters to be replaced inside the format stringThe function snprintf returns the number of characters that are in the format string after the formatting is applied.
Note: Null character
\0is not counted for thesizeargument or the return value of thesnprintffunction.
snprintf functionThe following example copies 15 characters from the string data to the character array arr and prints out the data in the arr array:
#include<stdio.h>int main() {const size_t size = 15;char arr[50];char * data = "Edpresso Shots! Are Fun!";int total_chars = snprintf(arr, size, "%s\n", data);printf("%s\nTotal Characters: %d\nCharacters Copied: %d", arr, total_chars, size);return 0;}
As seen in the above example, the format string after format processing is applied becomes Edpresso Shots! Are Fun!\n, which comprises of 25 characters (including the new line \n character). Since the size is 15, only Edpresso Shots\n is copied. However, according to the format string above, Edpresso Shots! should have been copied, not Edpresso Shots\n.
We can take this to mean that characters initially in the format string have a higher priority than the characters that are replaced inside the format string later on.
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