| Macros | |
| EXIT_FAILURE | EXIT_FAILURE |
| EXIT_SUCCESS | EXIT_SUCCESS |
| MB_CUR_MAX | Maximum number of bytes in a multi-byte character in the current locale |
| RAND_MAX | RAND_MAX |
| Types | |
| div_t | Structure containing quotient and remainder after division of an int |
| ldiv_t | Structure containing quotient and remainder after division of a long |
| lldiv_t | Structure containing quotient and remainder after division of a long long |
| Integer arithmetic functions | |
| abs | Return an integer absolute value |
| div | Divide two ints returning quotient and remainder |
| labs | Return a long integer absolute value |
| ldiv | Divide two longs returning quotient and remainder |
| llabs | Return a long long integer absolute value |
| lldiv | Divide two long longs returning quotient and remainder |
| Memory allocation functions | |
| calloc | Allocate space for an array of objects and initialize them to zero |
| free | Frees allocated memory for reuse |
| malloc | Allocate space for a single object |
| realloc | Resizes allocated memory space or allocates memory space |
| String to number conversions | |
| atof | Convert string to double |
| atoi | Convert string to int |
| atol | Convert string to long |
| atoll | Convert string to long long |
| strtod | Convert string to double |
| strtof | Convert string to float |
| strtol | Convert string to long |
| strtoll | Convert string to long long |
| strtoul | Convert string to unsigned long |
| strtoull | Convert string to unsigned long long |
| Pseudo-random sequence generation functions | |
| rand | Return next random number in sequence |
| srand | Set seed of random number sequence |
| Search and sort functions | |
| bsearch | Search a sorted array |
| qsort | Sort an array |
| Environment | |
| atexit | Set function to be execute on exit |
| exit | Terminates the calling process |
| Number to string conversions | |
| itoa | Convert int to string |
| lltoa | Convert long long to string |
| ltoa | Convert long to string |
| ulltoa | Convert unsigned long long to string |
| ultoa | Convert unsigned long to string |
| utoa | Convert unsigned to string |
| Multi-byte/wide character conversion functions | |
| mblen | Determine number of bytes in a multi-byte character |
| mblen_l | Determine number of bytes in a multi-byte character |
| Multi-byte/wide string conversion functions | |
| mbstowcs | Convert multi-byte string to wide string |
| mbstowcs_l | Convert multi-byte string to wide string using specified locale |
| mbtowc | Convert multi-byte character to wide character |
| mbtowc_l | Convert multi-byte character to wide character |