What does this C program do?

Question

#include <stdio.h>

int main(){

    char c;

    while((c = getchar()) != EOF){
        if(c >= 'A' && c <= 'Z')
            c = c - 'A' + 'a';
        putchar(c);
    }

    return 0;
}

Came across this C code in MIT's Practical Programming in C. Can anyone explain how this program works?

When you debug it, what do the runtime values become? When you run it, what is the input and resulting output? — David, Oct 01 '16 at 12:18
Ask a more specific question. Don't make us explain everything starting from `#include` onwards. What is it specifically about that program that you don't understand? — kaylum, Oct 01 '16 at 12:20
@nAin, BLUEPIXY in his comment highlights that the code your posted will have trouble handling the character 0xFF correctly unless `char c` is replaced with `int c`. More details [here](//stackoverflow.com/a/3866104/5420829). — Андрей Беньковский, Oct 01 '16 at 13:54

score 3 · Accepted Answer · answered Oct 01 '16 at 12:22

3

The program converts any input into lower case output.

You would have recognized this yourself, if you ran it, debugged it, or just made a paper test for this.

answered Oct 01 '16 at 12:22

René Hoffmann

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What does this C program do?

1 Answers1