#152 [Bug] Console Input Loop C Template

[Daimao]

The Console Input Loop C Template does not work properly. Entering a character other than a/q will not produce the invalid input message. I quickly hacked a fix that both maintains the original behavior and keeps it as simplified as possible (for the benefit of new coders). Here it is:

#include <stdio.h>

void Foo() {
    printf("Hello World!\n");
}

int main(int argc, char **argv) {
    char input = 0;

    printf("Hello! This is a console application.\n");
    printf("Press q to quit, press a to execute foo.\n");
    while(1) {
        if(scanf("%c",&input) == 1) {
            if(input == 'a') {
                Foo();
            } else if(input == 'q') {
                break;
            } else if(input != '\n' && input != ' ') {
                printf("Invalid input! Ignoring...\n");
            }
        }
    }

    return 0;
}

[Daimao]

Alternatively the following solution will also work:

#include <stdio.h>

void Foo() {
    printf("Hello World!\n");
}

int main(int argc, char** argv) {
    char input = 0;

    printf("Hello! This is a console application.\n");
    printf("Press q to quit, press a to execute foo.\n");
    while(1) {
        if(scanf(" %c",&input) == 1) {
            if(input == 'a') {
                Foo();
            } else if(input == 'q') {
                break;
            } else {
                printf("Invalid input! Ignoring...\n");
            }
        }
    }

    return 0;
}

However it is debatable if this one is easier for a novice to understand than my initial submission. However, it would potentially have them reading the scanf() documentation/references/manpage, which is a good thing.

[orwelldevcpp]

I have updated the input loop projects for both C and C++ to always produce some kind of output when the return key is pressed. For example, the C file now looks like this:

#include <stdio.h>

void Foo() {
    printf("Hello World!\n");
}

int main(int argc, char** argv) {
    char input = 0;

    printf("Hello! This is a console application.\n");
    printf("Press q to quit, press a to execute foo.\n");
    while(1) {
        if(scanf("%c",&input) == 1) {
            if(input == 'a') {
                Foo();
            } else if(input == 'q') {
                break;
            } else if(input != '\n') {
                printf("Unknown command '%c'! Ignoring...\n",input);
            }
        } else {
            printf("Invalid input! Ignoring...\n");
        }
    }

    return 0;
}