Understanding C Program Output with Number Literals

The provided C code snippet demonstrates how different types of integer literals (decimal, octal, and hexadecimal) are interpreted and printed using the printf function with the %d format specifier.

Let's break down the printf statement: printf("%d%d%d", 62, 062, 0x62);

The %d format specifier is used to print an integer value in its decimal representation.

The arguments provided to printf are:

• 62: This is a standard decimal integer literal. Its value is simply 62.
• 062: This literal starts with a 0, indicating it is an octal (base-8) integer literal. To find its decimal value, we convert from base 8 to base 10. $$ 062_8 = 0 \times 8^2 + 6 \times 8^1 + 2 \times 8^0 $$ $$ = 0 \times 64 + 6 \times 8 + 2 \times 1 $$ $$ = 0 + 48 + 2 = 50_{10} $$ So, the value of 062 is 50 in decimal.
• 0x62: This literal starts with 0x, indicating it is a hexadecimal (base-16) integer literal. To find its decimal value, we convert from base 16 to base 10. $$ 0x62_{16} = 6 \times 16^1 + 2 \times 16^0 $$ $$ = 6 \times 16 + 2 \times 1 $$ $$ = 96 + 2 = 98_{10} $$ So, the value of 0x62 is 98 in decimal.

The printf function will print these decimal values consecutively without any separators as specified by the format string "%d%d%d".

The values to be printed are:

• First %d prints the decimal value of 62, which is 62.
• Second %d prints the decimal value of 062, which is 50.
• Third %d prints the decimal value of 0x62, which is 98.

Combining these outputs in order gives the final result: 62 followed by 50 followed by 98.

Output string: "62" + "50" + "98" = "625098"

Number Literal Conversions Summary

Therefore, the output of the code is 625098.

Revision Table: C Integer Literals and printf

Additional Information on C Number Systems

C supports different number literal formats to allow programmers to represent values conveniently based on context. Understanding these formats is crucial for correctly interpreting code.

• Decimal: The most common format. Digits 0-9. No prefix required.
• Octal: Used less frequently in modern code, but important to recognize. Digits 0-7. Must be prefixed with a single 0.
• Hexadecimal: Very common, especially in low-level programming, bitwise operations, and memory addresses. Digits 0-9 and letters A-F (case-insensitive). Must be prefixed with 0x or 0X.

When using printf with %d, the literal's base (octal, hex) is used to determine the *value*, but that value is then *printed* in base 10. If you wanted to print the octal or hexadecimal representation of a number, you would use %o or %x/%X respectively.