C String Functions: strchr, strrchr, strcspn, strspn, strpbrk, strstr, strtok, Study notes of Engineering

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CSE294A

Introduction to C Programming for Engineers

Lecture

Jeffrey Miller, Ph.D.

C String Functions

char strchr (const char, int);

Locates the first occurrence of the characterdenoted by the ASCII value of the integerpassed in the string

Returns a pointer to the character in the string ifexists - Returns a NULL pointer if the character is notin the string

C String Functions

size_t strcspn (const char, const char);

Determines and returns the length of the initialsegment of the first string consisting ofcharacters not contained in the second string char *s = “hello world”; char *s2 = “wow”; int length = strcspn(s1, s2); // returns 4

C String Functions

size_t strspn (const char, const char);

Determines and returns the length of the initialsegment of the first string consisting only ofcharacters contained in the second string char *s1 = “heeee haw”; char *s2 = “he”; int length = strspn(s1, s2); // returns 5

C String Functions

char* strstr (const char, const char);

Locates the first occurrence in the first string ofthe second string

If the second string is found in the first string, apointer to the string in the first string is returned - If not, a NULL pointer is returned

C String Functions

char* strtok (char, const char);

Breaks the first string into “tokens” separatedby characters contained in the second string

The first call to this function contains a stringas the first parameter, and subsequent calls tocontinue tokenizing the same string containsNULL as the first parameter - A pointer to the current token is returned byeach call - If there are no more tokens, NULL is returned

Homework

Homework #7 is posted!