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Discussion: Hello, stdin

Explore how the setbuf function manages output buffering in C, controlling when text appears during program execution. Understand the differences between unbuffered, block buffered, and line buffered modes. Learn why pressing Enter flushes the output buffer and how buffering affects standard input and output behavior in stream I/O. This lesson helps you grasp essential concepts for managing interactive and non-interactive I/O in C programming.

Run the code

Now, it's time to execute the code and observe the output. After you press the "Run" button, press "Enter" to see the output.

#include <stdio.h>

int main()
{
    char buffer[BUFSIZ]; /* BUFSIZ is a constant defined in stdio.h */
    setbuf(stdout, buffer);
    puts("Wait for it!");
    puts("Wait for it!");
    puts("Now!");
    getchar();
    puts("Whew!");
    return(0);
}
C code for the given puzzle

Understanding the output

No output is generated when the program starts. Press the "Enter" key, and the following text appears: ...

Wait for it!
Wait for it!
Now!
Whew!
Code output
...