> ## 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 long The `long long` data type in C is a standard integer type introduced in the C99 specification that guarantees a minimum storage width of 64 bits. It provides the largest standard integer capacity available in the language, strictly adhering to the hierarchical type constraint that `sizeof(long long) >= sizeof(long) >= sizeof(int)`. ## Syntax and Declarations The type can be declared as signed or unsigned. By default, omitting the sign specifier results in a signed integer. ```c theme={"dark"} long long var1; // Implicitly signed 64-bit integer signed long long var2; // Explicitly signed 64-bit integer unsigned long long var3; // Unsigned 64-bit integer ``` ## Memory Footprint and Value Ranges While the C standard dictates a *minimum* of 64 bits, on most modern architectures (both 32-bit and 64-bit systems), `long long` is exactly 64 bits (8 bytes). To accommodate ones' complement and sign-magnitude architectures in C99 through C17, the standard guarantees the following minimum value ranges: * **`signed long long`**: $-(2^{63}-1)$ to $2^{63}-1$ * (-9,223,372,036,854,775,807 to 9,223,372,036,854,775,807) * *Note: While C23 formally mandates two's complement representation (extending the minimum to $-2^{63}$), the historical and strict C99 guaranteed minimum is $-(2^{63}-1)$.* * **`unsigned long long`**: $0$ to $2^{64}-1$ * (0 to 18,446,744,073,709,551,615) ## Literal Suffixes According to C standard rules for integer constants, an unsuffixed decimal literal automatically assumes the type `long long int` if its value cannot be represented by an `int` or `long int`. Suffixes are strictly required only when you want to explicitly force a smaller value to be typed as `long long`, or when you are writing an unsigned decimal constant that exceeds `LLONG_MAX`. ```c theme={"dark"} // Automatically typed as long long if it exceeds long capacity long long auto_val = 9223372036854775807; // 'LL' or 'll' forces a smaller value to be signed long long long long forced_signed = 42LL; // 'ULL', 'ull', 'Ull', or 'uLL' forces unsigned long long. // Required for unsigned decimal literals > LLONG_MAX. unsigned long long max_unsigned = 18446744073709551615ULL; ``` ## Format Specifiers To perform standard I/O operations (such as `printf` and `scanf`) with `long long` variables, you must use the `ll` (double-ell) length modifier combined with the appropriate conversion specifier. ```c theme={"dark"} long long s_val = -42LL; unsigned long long u_val = 42ULL; // Signed decimal printf("%lld\n", s_val); // or %lli // Unsigned decimal printf("%llu\n", u_val); // Unsigned hexadecimal (lowercase / uppercase) printf("%llx\n", u_val); printf("%llX\n", u_val); // Unsigned octal printf("%llo\n", u_val); ``` ## Standard Library Limits The `` header provides preprocessor macros that define the exact boundary values for `long long` types on the target compilation platform. ```c theme={"dark"} #include #include int main() { printf("Min signed: %lld\n", LLONG_MIN); printf("Max signed: %lld\n", LLONG_MAX); printf("Max unsigned: %llu\n", ULLONG_MAX); return 0; } ```

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