Strstr() function in C++
The stristr() function searches for the first occurrence of a string inside another string. This function is binary-safe and case-insensitive.
C++ strstr() Function
In C++, strstr() is an inbuilt string handling function used to find the first occurrence of a substring in a string. It is defined in the string.h header file. The process of matching stops at ''.
Strpbrk() in C
strpbrk() is used to find the first character of the first string and match it to any character of the second string. It returns a pointer to the character of the first string that matches the character of the second string or NULL if no matches are found.
PHP String Functions
PHP provides strpos() function to check if a string contains a specific substring. It returns the position of the first occurrence of a substring in a string. Additionally, it checks if the substring is at the start of the main string.
C String Functions
strlen(string_name)returns the length of a string.strcpy(destination, source)copies the contents of the source string to the destination string.strcat(first_string, second_string)concatenates or joins the first string with the second string.strcmp(first_string, second_string)strrev(string)strlwr(string)
Implementing strStr() in C++
The implementation of strStr() method in C++ has a time complexity of O(MN), where M and N are the lengths of the input haystack and needle string. The outer loop should be from 0 to the length of M-N+1, and the inner loop checks if the substring of haystack matches the needle.
Finding a Substring in a String
The String class provides two accessor methods – indexOf and lastIndexOf that return the position within the string of a specific character or substring. indexOf searches forward from the beginning of the string, and lastIndexOf searches backward from the end of the string.
Handling Empty Needle Strings
For the purpose of this problem, return 0 when the needle is an empty string. This is consistent with C’s strstr() and Java’s indexOf().