Integer literal in C/C++ (Prefixes and Suffixes)

Integer literals in C are numeric values written directly in the source code to represent integer constants. They can be modified using prefixes to specify the base (decimal, octal, hexadecimal, binary) and suffixes to specify the data type (int, long, unsigned, etc.).

Integer literals are of two types −

• Prefixes − Indicate the number base. For example, 0x10 represents hexadecimal value 16.
• Suffixes − Specify the data type. For example, 123LL represents a long long integer.

Syntax

// Prefixes
decimal_literal     (no prefix)
0octal_literal      (prefix 0)
0xhexadecimal       (prefix 0x or 0X)
0bbinary            (prefix 0b or 0B, C23)

// Suffixes
integer_literal[u|U][l|L|ll|LL]

Prefixes for Number Bases

Different prefixes specify the base of the number −

#include <stdio.h>

int main() {
    printf("Decimal 213: %d\n", 213);        /* Base 10 */
    printf("Octal 0213: %d\n", 0213);        /* Base 8 */
    printf("Hex 0x213A: %d\n", 0x213A);      /* Base 16 */
    printf("Binary 0b101: %d\n", 0b101);     /* Base 2 (C23) */
    return 0;
}

Decimal 213: 213
Octal 0213: 139
Hex 0x213A: 8506
Binary 0b101: 5

Suffixes for Data Types

Suffixes specify the integer type and signedness −

#include <stdio.h>

int main() {
    printf("Long: %ld\n", 1234567890123456789L);
    printf("Long Long: %lld\n", 1234567890123456789LL);
    printf("Unsigned: %u\n", 12345U);
    printf("Unsigned Long Long: %llu\n", 12345678901234567890ULL);
    return 0;
}

Long: 1234567890123456789
Long Long: 1234567890123456789
Unsigned: 12345
Unsigned Long Long: 12345678901234567890

Common Suffix Combinations

Conclusion

Integer literals in C provide flexible ways to represent numbers in different bases using prefixes and specify exact data types using suffixes. This ensures precise control over numeric values and their storage requirements in C programs.