# <limits.h>

**[<limits.h>](https://en.cppreference.com/w/c/header/limits)** provides platform-specific integer type limits: `INT_MAX`, `INT_MIN`, `UINT_MAX`, `LONG_MAX`, etc. Use these when writing portable code that works correctly regardless of whether integers are 32 or 64 bits.

Never hardcode values like `2147483647` directly; use the macros instead.

## Example

This example queries integer limits and demonstrates overflow checking.

```c
// compile: gcc -o limitsexample limitsexample.c
// run: ./limitsexample
// description: query integer limits and check for overflow

#include <limits.h>
#include <stdio.h>

int main() {
    printf("INT_MAX = %d\n", INT_MAX);
    printf("INT_MIN = %d\n", INT_MIN);
    printf("UINT_MAX = %u\n", UINT_MAX);
    printf("LONG_MAX = %ld\n", LONG_MAX);
    
    int a = INT_MAX, b = 1;
    if (a > INT_MAX - b)
        printf("INT_MAX + 1 would overflow\n");
    
    unsigned int u = UINT_MAX;
    printf("UINT_MAX + 1 = %u (wraps to 0)\n", u + 1);
    
    return 0;
}
```

## Common macros

**Signed integer limits**:
- `CHAR_MIN`, `CHAR_MAX`: char (may be signed or unsigned depending on platform)
- `SCHAR_MIN`, `SCHAR_MAX`: signed char
- `SHRT_MIN`, `SHRT_MAX`: short
- `INT_MIN`, `INT_MAX`: int
- `LONG_MIN`, `LONG_MAX`: long
- `LLONG_MIN`, `LLONG_MAX`: long long

**Unsigned integer limits**:
- `UCHAR_MAX`: unsigned char
- `USHRT_MAX`: unsigned short
- `UINT_MAX`: unsigned int
- `ULONG_MAX`: unsigned long
- `ULLONG_MAX`: unsigned long long (C99)

**Character and bit information**:
- `CHAR_BIT`: number of bits in char (typically 8)
- `CHAR_MIN`, `CHAR_MAX`: depends on signedness of char on platform
- `MB_LEN_MAX`: max bytes in multibyte character

**Portable sizing**:
- Use these macros instead of hardcoding 32 or 64 for portable code
- For fixed-width types, use `<stdint.h>` instead (e.g., `INT32_MAX`)
- `<limits.h>` defines platform-dependent limits