An effective value is the value a literal contributes after its spelling, base, suffix, type, and required conversions are taken into account. For example, int x = 0xFFFF'FFFF; does not guarantee that x receives −1: the literal's effective value is +4,294,967,295, and conversion to a signed value is not universally guaranteed. section 5.3
TAKEAWAY rules:
- Use decimal literals for negative values; do not rely on binary, octal, or hexadecimal spellings to represent negative values. section 5.3
- Treat the base prefix as significant: it determines how the literal is read and can influence its deduced type. section 5.3
- Use suffixes deliberately: U forces unsigned, L requests at least long, LL requests long long, and WB selects a bit-precise type in C23. section 5.3
Table 5.3 Examples for literals and their types, under the supposition that signed and unsigned have the commonly used representation with 32 bits
| Literal 𝑥 | Value | Type | Value of -𝑥 |
| 2'147'483'647 | +2,147,483,647 | signed | -2,147,483,647 |
| 2'147'483'648 | +2,147,483,648 | signed long | -2,147,483,648 |
| 4'294'967'295 | +4,294,967,295 | signed long | -4,294,967,295 |
0x7FFF'FFFF |
+2,147,483,647 | signed | -2,147,483,647 |
0x8000'0000 |
+2,147,483,648 | unsigned | +2,147,483,648 |
0xFFFF'FFFF |
+4,294,967,295 | unsigned | +1 |
| 1 | +1 | signed | -1 |
| 1U | +1 | unsigned | +4,294,967,295 |
Compare literal spellings with their effective values, types, and negated results under a commonly used 32-bit representation. section 5.3
Table 5.4 Suffixes for integer literals and their types
| Suffix | Type |
l or L |
At least long |
ll or LL |
long long |
wb or WB |
_BitInt(𝑁) for sufficiently large 𝑁 |
u or U |
Force unsigned |
Use the suffix table to check how spelling changes an integer literal's type or signedness. section 5.3
