The string functions are declared in the include file STRING.H. They allow you to compare strings, copy them, search for strings and characters, and perform various other operations.
Routines beginning with _f are model-independent versions of the corresponding routines and are useful in mixed-model programs. These routines can be called from any point in the program, regardless of which model is being used.
| Routine | Use |
| strcat, _fstrcat | Append one string to another |
| strchr, _fstrchr | Find first occurrence of a given character in a string |
| strcmp, _fstrcmp | Compare two strings |
| strcpy, _fstrcpy | Copy one string to another |
| strcspn, _fstrcspn | Find first occurrence of a character from a given character set in a string |
| _strdup, _fstrdup, _nstrdup | Duplicate a string |
| strerror | Maps an error number to a message string |
| _strerror | Maps a user-defined error message to a string |
| _stricmp, _fstricmp | Compare two strings without regard to case |
| strlen, _fstrlen | Find length of string |
| _strlwr, _fstrlwr | Convert string to lowercase |
| strncat, _fstrncat | Append characters of a string |
| strncmp, _fstrncmp | Compare characters of two strings |
| strncpy, _fstrncpy | Copy characters of one string to another |
| _strnicmp, _fstrnicmp | Compare characters of two strings without regard to case |
| _strnset, _fstrnset | Set characters of a string to a given character |
| strpbrk, _fstrpbrk | Find first occurrence of a character from one string in another |
| strrchr, _fstrrchr | Find last occurrence of a given character in string |
| _strrev, _fstrrev | Reverse a string |
| _strset, _fstrset | Set all characters of a string to a given character |
| strspn, _fstrspn | Find first substring from a given character set in a string |
| strstr, _fstrstr | Find first occurrence of a given string in another string |
| strtok, _fstrtok | Find next token in a string |
| _strupr, _fstrupr | Convert a string to uppercase |
All string functions work on null-terminated character strings. When working with character arrays that do not end with a null character, you can use the buffer-manipulation routines, described in “Buffer Manipulation”.