> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # C long The `long` keyword in C is a fundamental integer data type (implicitly `long int`) that guarantees a minimum storage size of 32 bits. It provides a larger or equal value range compared to the standard `int` type, depending on the compiler and the target architecture's data model. ## Memory Size and Data Models The exact byte size of `long` is implementation-defined. While the C standard mandates a minimum of 32 bits, its actual size diverges across different 64-bit environments: * **ILP32 (32-bit systems):** 32 bits (4 bytes). * **LLP64 (64-bit Windows):** 32 bits (4 bytes). * **LP64 (64-bit Unix/Linux/macOS):** 64 bits (8 bytes). ## Syntax and Modifiers By default, `long` is signed, utilizing two's complement representation. It can be explicitly modified using the `unsigned` keyword to shift the representable range to strictly non-negative values, effectively doubling the maximum positive limit. ```c theme={"dark"} // Signed long declarations (all are semantically identical) long a; long int b; signed long c; signed long int d; // Unsigned long declarations (all are semantically identical) unsigned long e; unsigned long int f; ``` ## Literal Suffixes When parsing integer literals, the C compiler assigns the `int` type by default if the value fits. To explicitly force a literal to be evaluated as a `long`, append the `L` or `l` suffix (uppercase `L` is standard practice to avoid visual confusion with the digit `1`). For unsigned variants, combine `U` and `L`. ```c theme={"dark"} long signed_val = 2147483647L; unsigned long unsigned_val = 4294967295UL; ``` ## Format Specifiers When interfacing with standard I/O functions like `printf` and `scanf`, specific length modifiers (`l`) must be prepended to the integer conversion specifiers to prevent undefined behavior resulting from stack misalignment or truncation. * `%ld` or `%li`: Signed `long` * `%lu`: Unsigned `long` * `%lx` or `%lX`: Unsigned `long` in hexadecimal * `%lo`: Unsigned `long` in octal ```c theme={"dark"} #include int main(void) { long val = -123456L; unsigned long uval = 123456UL; printf("Signed: %ld\n", val); printf("Unsigned: %lu\n", uval); return 0; } ``` ## Standard Limits The absolute minimum and maximum representable values for the specific compilation target are exposed via macros in the `` standard library header. ```c theme={"dark"} #include int main(void) { long min_val = LONG_MIN; // Guaranteed to be <= -2147483647 long max_val = LONG_MAX; // Guaranteed to be >= +2147483647 unsigned long umax_val = ULONG_MAX; // Guaranteed to be >= +4294967295 return 0; } ```

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