# C++ Notes: Common <cstring> functions

## Common <cstring> functions

Here are a number of useful functions work with character arrays (C-strings). The types of the parameters are cs=`char[]` or `char*`, c=`char/int`. Where `true` appears, zero is false and non-zero is true.

Type | Method | Description
--- | --- | ---
`#include <cstring>` (or older `<string.h>`)
int | strlen(const cs) | Returns the length of the c-string cs.
char* | strcpy(cs1, const cs2) | Copies cs2 to cs1. Returns the first parameter (usually ignored).
char* | strcat(cs1, const cs2) | Concatenates cs2 on the end of cs1. Returns the first parameter (usually ignored).
int | strcmp(const cs1, const cs2) | Returns one of three kinds of values: negative if cs1 < cs2, zero if cs1 == cs2, or positive if cs1 > cs2.
char* | strchr(const cs, c) | Returns a pointer to the first occurrence of c in cs or NULL if it isn't in the string.
char* | strstr(const cs1, const cs2) | Returns a pointer to the first occurrence of cs2 in cs1 or NULL if it isn't in the string.