puts() vs printf() for printing a string

In C, both puts() and printf() functions are used for printing a string on the console and are defined in <stdio.h> header file. In this article, we will discuss the differences in the usage and behavior of both functions.

puts() Function

The puts() function is used to write a string to the console and it automatically adds a new line character '\n' at the end.

Syntax

puts("str");

Parameters

• str: It takes a null-terminated string as the argument.

Return Value

• It returns a non-negative value if the output is successful, or End-of-File if an error occurs.

printf() Function

The printf() function is also used to print data on the console, but it can also be used to print the formatted data to the console based on a specified format string.

Syntax

printf("format_string", Arguments);

Parameters

• format_string: It can be a simple string or a string containing format specifiers.
• Arguments: It is the variable names whose value is to be printed.

Return Value

• It returns the number of characters successfully written to the console and a negative value if an error occurs.

Which of the following two should be preferred?

puts() can be preferred for printing a string because it is generally less costly(implementation of puts() is generally simpler than printf()), and if the string has formatting characters like '%s', then printf() would give unexpected results. Also, if str is a user input string, then the use of printf() might cause security issues.

Also, note that puts() move the cursor to the next line.

If you do not want the cursor to be moved to the next line, then you can use the following variation of puts().

fputs(str, stdout)

Difference between the printf() and puts()

Following are some differences between printf() and puts() functions in C:

You can try the following programs for testing the above-discussed differences between puts() and print().

Example 1

The below C program demonstrates the use of puts.

// C program to show the use of puts
#include <stdio.h>
int main()
{
    puts("Geek%sforGeek%s");
    getchar();
    return 0;
}

Geek%sforGeek%s

Example 2

The below C program demonstrated the use of fputs.

// C program to show the use of fputs
#include <stdio.h>
int main()
{
    fputs("Geeksfor", stdout);
    fputs("Geeks", stdout);

    return 0;
}

GeeksforGeeks

Example 3

The below C program demonstrates the unexpected behavior when %s is used in printf.

// C program to show the unexpected behaviour
// when %s is used in printf
#include <stdio.h>
int main()
{
    // % is intentionally put here to show the unexpected
    // behaviour when %s is used in printf
    printf("Geek%sforGeek%s");
    getchar();
    return 0;
}

Geek0>z??forGeek;>z??

kartik

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Article Tags :

• C Language
• C-Input and Output Quiz