In `printf("element %zu is %g\n", i, 9.0)`, the quoted text and `9.0` represent fixed values written directly in the program. They are literals. The names `printf` and `i` are identifiers, not literals. section 2.1
A literal’s spelling helps determine what value it specifies:
- `123` is a decimal integer literal; `077` is octal and has value 63; `0xFFFF` is hexadecimal. section 5.3
- `1.7E-13` is a decimal floating-point literal. `0x1.7aP-13` is a hexadecimal floating-point form. section 5.3
- `"first line\n"` is a string literal: text known at compile time. Consecutive string literals are concatenated, so a long string can be split across source lines. section 5.3
**TAKEAWAY:** Numerical literals are never negative. In `-34`, the minus sign is a negation operator applied to the literal `34`; in `-1.5E-23`, the exponent’s minus sign is part of the floating-point literal. Every literal also has a type, which is a separate question from whether its value is positive. section 5.3
A decimal integer literal takes the first signed integer type that fits its value. For example, if the largest `signed` value is 32767, `32768` requires `signed long`; `-32768` therefore also has type `signed long`. Do not infer a literal’s type from the apparent type of a value after negation. section 5.3
Table 5.3. Examples for constants and their types. This is under the supposition that signed and unsigned have the commonly used representation with 32 bits (view table figure)
| Constant x |
Value |
Type |
Value of –x |
|---|---|---|---|
| 2147483647 | +2147483647 | signed | –2147483647 |
| 2147483648 | +2147483648 | signed long | –2147483648 |
| 4294967295 | +4294967295 | signed long | –4294967295 |
| 0x7FFFFFFF | +2147483647 | signed | –2147483647 |
| 0x80000000 | +2147483648 | unsigned | +2147483648 |
| 0xFFFFFFFF | +4294967295 | unsigned | +1 |
| 1 | +1 | signed | –1 |
| 1U | +1 | unsigned | +4294967295 |
Compare the listed types and negated results for decimal, hexadecimal, and `U`-suffixed constants. The table’s results depend on its stated 32-bit representation assumption. section 5.3
Integer literals also appear in preprocessor conditions used to reject an unsuitable execution platform during compilation. Such conditions evaluate macros and integer literals; an unknown identifier evaluates to 0. section 8.1.5
