| atof | converts a string to a double |
| atoi | converts a string to an integer |
| atol | converts a string to a long |
| isalnum | true iff a character is alphanumeric |
| isalpha | true iff a character is alphabetic |
| iscntrl | true iff a character is a control character |
| isdigit | true iff a character is a digit |
| isgraph | true iff a character is a graphical character |
| islower | true iff a character is lowercase |
| isprint | true iff a character is a printing character |
| ispunct | true iff a character is punctuation |
| isspace | true iff a character is a space character |
| isupper | true iff a character is an uppercase character |
| isxdigit | true iff a character is a hexadecimal character |
| memchr | searches an array for the first occurrence of a character |
| memcmp | compares two buffers |
| memcpy | copies one buffer to another |
| memmove | moves one buffer to another |
| memset | fills a buffer with a character |
| strcat | concatenates two strings |
| strchr | finds the first occurrence of a character in a string |
| strcmp | compares two strings |
| strcoll | compares two strings in accordance to the current locale |
| strcpy | copies one string to another |
| strcspn | searches one string for any characters in another |
| strerror | returns a text version of a given error code |
| strlen | returns the length of a given string |
| strncat | concatenates a certain amount of characters of two strings |
| strncmp | compares a certain amount of characters of two strings |
| strncpy | copies a certain amount of characters from one string to another |
| strpbrk | finds the first location of any character in one string, in another string |
| strrchr | finds the last occurrence of a character in a string |
| strspn | returns the length of a substring of characters of a string |
| strstr | finds the first occurrence of a substring of characters |
| strtod | converts a string to a double |
| strtok | finds the next token in a string |
| strtol | converts a string to a long |
| strtoul | converts a string to an unsigned long |
| strxfrm | converts a substring so that it can be used by string comparison functions |
| tolower | converts a character to lowercase |
| toupper | converts a character to uppercase |