Character Sets and ASCII

char stores a character code. ASCII assigns values 0–127 to common English letters, digits, symbols, and control characters.

Converting between characters and integers

Convert a character to an integer to inspect its code, or convert a value from 0–127 to char to obtain the matching ASCII character. A digit character is not the number itself: '7' - '0' produces integer 7.

#include <stdio.h>

int main(void) {
    char letter = 'A';
    int code = (unsigned char) letter;
    char next = (char) (code + 1);
    printf("%c = %d, next = %c\n", letter, code, next);
    return 0;
}

Traversing ASCII

Control characters have no visible glyph, so a program should label values 0–31 and 127 separately.

for (int value = 0; value <= 127; value++) {
    if (value >= 32 && value <= 126) {
        printf("%3d  %c\n", value, (char) value);
    } else {
        printf("%3d  control\n", value);
    }
}