Understanding ASCII in C

In C, characters (char) are stored internally as numeric integer codes following the American Standard Code for Information Interchange (ASCII).

• 'A' $→$ 65, 'Z' $→$ 90
• 'a' $→$ 97, 'z' $→$ 122
• '0' $→$ 48, '9' $→$ 57

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Complete C Source Code

c (ISO Standard)
Run in Compiler.cCopy
#include <stdio.h>

void printAsciiInfo(char ch) {
    printf("Character: '%c' | Decimal ASCII: %3d | Hex: 0x%02X | Octal: %03o\n",
           ch, (unsigned char)ch, (unsigned char)ch, (unsigned char)ch);
}

int main() {
    char sampleChars[] = {'A', 'z', '0', '$', '\n', '\t'};
    int count = sizeof(sampleChars) / sizeof(sampleChars[0]);

    printf("ASCII Code Inspector in C:\n\n");
    for (int i = 0; i < count; i++) {
        printAsciiInfo(sampleChars[i]);
    }

    return 0;
}

Sample Output

text (ISO Standard)
Copy
ASCII Code Inspector in C:

Character: 'A' | Decimal ASCII:  65 | Hex: 0x41 | Octal: 101
Character: 'z' | Decimal ASCII: 122 | Hex: 0x7A | Octal: 172
Character: '0' | Decimal ASCII:  48 | Hex: 0x30 | Octal: 060
Character: '$' | Decimal ASCII:  36 | Hex: 0x24 | Octal: 044
Character: '
' | Decimal ASCII:  10 | Hex: 0x0A | Octal: 012
Character: '	' | Decimal ASCII:   9 | Hex: 0x09 | Octal: 011

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Complexity Analysis

• Time Complexity: O(1) constant time casting.
• Space Complexity: O(1) stack variables.

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Related Guides

• Format specifiers in Format Specifiers in C.
• Character analysis in Count Vowels and Consonants in C.