C Library - sprintf() function

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The C Library sprintf() function allows you to create strings with specified formats, similar to printf(), but instead of printing to the standard output, it stores the resulting string in a character array provided by the user.

Syntax

Following is the C library syntax of the sprintf() function −

int sprintf(char *str, const char *format, ...);

Parameters

This function accepts the following parameters −

• str : A pointer to an array of characters where the resulting string will be stored.
• format : A pointer to a null-terminated string that contains the text to be written to the string str. This string may contain format specifiers that dictate how subsequent arguments are converted and formatted into the resulting string.

Return Value

The sprintf() function returns the number of characters written to the string str, excluding the null-terminating character.

Example 1: Formatting Floating Point Numbers

Here, sprintf() formats a floating-point number with two decimal places.

Below is the illustration of the C library sprintf() function.

#include <stdio.h>

int main() {
    char buffer[100];
    float pi = 3.14159;
    sprintf(buffer, "The value of pi is %.2f.", pi);
    printf("%s\n", buffer);
    return 0;
}

Output

The above code produces following result−

The value of pi is 3.14.

Example 2: Combining Strings and Integers

This example showcases how sprintf() can combine strings and integers into a single formatted string.

#include <stdio.h>

int main() {
    char buffer[100];
    int age = 30;
    char name[] = "John";
    sprintf(buffer, "%s is %d years old.", name, age);
    printf("%s\n", buffer);
    return 0;
}

Output

After execution of above code, we get the following result −

John is 30 years old.