Built in functions in C

String Manipulation Functions


char *strcpy (char *dest, char *src); 
Copy src string into dest string.
char *strncpy(char *string1, char *string2, int n); 
Copy first n characters of string2 to stringl .
int strcmp(char *string1, char *string2); 
Compare string1 and string2 to determine alphabetic order.
int strncmp(char *string1, char *string2, int n); 
Compare first n characters of two strings.
int strlen(char *string); 
Determine the length of a string.
char *strcat(char *dest, const char *src); 
Concatenate string src to the string dest.
char *strncat(char *dest, const char *src, int n); 
Concatenate n chracters from string src to the string dest.
char *strchr(char *string, int c); 
Find first occurrence of character c in string.
char *strrchr(char *string, int c); 
Find last occurrence of character c in string.
char *strstr(char *string2, char string*1); 
Find first occurrence of string string1 in string2.
char *strtok(char *s, const char *delim) ;
Parse the string s into tokens using delim as delimiter.


Memory Management Functions

void *calloc(int num elems, int elem_size); 
Allocate an array and initialise all elements to zero .
void free(void *mem address);
Free a block of memory.
void *malloc(int num bytes); 
Allocate a block of memory.
void *realloc(void *mem address, int newsize); 
Reallocate (adjust size) a block of memory.

Buffer Manipulation


void* memcpy(void* s, const void* ct, int n);
Copies n characters from ct to s and returns s. s may be corrupted if objects overlap.
int memcmp(const void* cs, const void* ct, int n);
Compares at most (the first) n characters of cs and ct, returning negative value if cs<ct, zero if cs==ct, positive value if cs>ct.
void* memchr(const void* cs, int c, int n);
Returns pointer to first occurrence of c in first n characters of cs, or NULL if not found.
void* memset(void* s, int c, int n); 
Replaces each of the first n characters of s by c and returns s.
void* memmove(void* s, const void* ct, int n); 
Copies n characters from ct to s and returns s. s will not be corrupted if objects overlap.