string.h

string.h is a built-in header file in C that provides several functions for string manipulation. To access these functions in C++, we can #include <cstring>, but they still output a character pointer, not a string.

Data types

• size_t: the unsigned integer type. Guaranteed to be large enough to represent the size of the largest possible object on the platform you’re using.

Functions

• size_t strlen(const char *str): takes in a string and counts characters up to but not including the null character.
• char* strcpy(char *dest, char *src): copies one string to another string.
• char* strncpy(char *dest, char *src, size_t n): memory-safe implementation of strcpy, copies specified number of characters.
• char* strcat(char *dest, const char *src): appends source string to the back of the destination string, including the null character.
• char* strncat(char *dest, char *src, size_t n): memory-safe implementation of strcat.
• int strcmp(const char *fir, const char *sec): compares strings against each other. If both are identical, it spits out a zero. If the first comes before the second in the dictionary, it spits out a negative number. Otherwise it spits out a positive number.
• int strncmp(const char *p, const char *q, int n): memory-safe implementation of strcmp.
• char* strchr(char *s, char c): returns a pointer to the first occurrence of c — we can get the index by subtracting the pointer to s.
• char* strstr(char *s1, char *s2): returns pointer to beginning of sub-string occurrence.
• void* memcpy(void *dest, const void *src, size_t n): copies some memory from source to destination. Note a useful application is to set n as some sizeof(<type>).