# Standard library header <cstring>

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This header was originally in the C standard library as `<string.h>`.

This header is for C-style null-terminated byte strings.

### Macros

NULL | implementation-defined null pointer constant (macro constant)

### Types

size_t | unsigned integer type returned by the `sizeof` operator (typedef)

### Functions

##### String manipulation

strcpy | copies one string to another (function)
strncpy | copies a certain amount of characters from one string to another (function)
strcat | concatenates two strings (function)
strncat | concatenates a certain amount of characters of two strings (function)
strxfrm | transform a string so that strcmp would produce the same result as strcoll (function)

##### String examination

strlen | returns the length of a given string (function)
strcmp | compares two strings (function)
strncmp | compares a certain number of characters from two strings (function)
strcoll | compares two strings in accordance to the current locale (function)
strchr | finds the first occurrence of a character (function)
strrchr | finds the last occurrence of a character (function)
strspn | returns the length of the maximum initial segment that consists of only the characters found in another byte string (function)
strcspn | returns the length of the maximum initial segment that consists of only the characters not found in another byte string (function)
strpbrk | finds the first location of any character from a set of separators (function)
strstr | finds the first occurrence of a substring of characters (function)
strtok | finds the next token in a byte string (function)

##### Character array manipulation

memchr | searches an array for the first occurrence of a character (function)
memcmp | compares two buffers (function)
memset | fills a buffer with a character (function)
memcpy | copies one buffer to another (function)
memmove | moves one buffer to another (function)

##### Miscellaneous

strerror | returns a text version of a given error code (function)

### Notes

- NULL is also defined in the following headers:
  - `<clocale>`
  - `<ctime>`
  - `<cstddef>`
  - `<cstdio>`
  - `<cwchar>`
- std::size_t is also defined in the following headers:
  - `<ctime>`
  - `<cstddef>`
  - `<cstdio>`
  - `<cuchar>` (since C++17)
  - `<cwchar>`

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