What is the role of the C language string output function puts()

The functions of the C language string output function puts(): 1. [puts()] will automatically add a newline character at the end of the string when displaying it; 2. [puts()] encounters an empty string The output stops when a character is reached, so you must ensure that there are null characters.

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C The role of the language string output function puts():

• puts() will automatically add a newline character at the end of the string when it is displayed.

• puts() Stops output when encountering a null character, so you must ensure that there is a null character.

The following two examples illustrate the two characteristics of puts() respectively.

Example 1:

/* put_out.c -- using puts() */
#include <stdio.h>
#define DEF "I am a #defined string."
int main(void)
{
    char str1[80] = "An array was initialized to me.";
    const char * str2 = "A pointer was initialized to me.";
 
    puts("I&#39;m an argument to puts().");
    puts(DEF);
    puts(str1);
    puts(str2);
    puts(&str1[5]);
    puts(str2+4);
 
    return 0;
}</stdio.h>

The output of this program is as follows:

I'm an argument to puts().
I am a #defined string.
An array was initialized to me.
A pointer was initialized to me.
ray was initialized to me.
inter was initialized to me.

As shown above, each string is on its own line because puts() will Automatically adds a newline character at the end.

Example 2:

/* nono.c -- no! */
#include <stdio.h>
int main(void)
{
    char side_a[] = "Side A";
    char dont[] = {&#39;W&#39;, &#39;O&#39;, &#39;W&#39;, &#39;!&#39; };
    char side_b[] = "Side B";
 
    puts(dont);   /* dont is not a string */
 
    return 0;
}</stdio.h>

The following is an example of this program. The results may be different every time it is run. The content output by different compilers may be different:

WOW!Side A

How does puts() know where to stop? This function stops output when it encounters a null character. Since dont lacks a terminating null character, it is not a string, so puts() doesn't know where to stop. It will keep printing the content in the memory after dont until a null character is found. In order to allow puts() to read the null character as quickly as possible, we put dont between side_a and side_b. The above is a running example of the program, output by different compilers Content may vary

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