StringFunctions.c

#include <stdio.h>
#include <string.h>

int main()
{
    char string1[] = "He";
    char string2[] = "Zhengjie";

    strlwr(string1); // converts a string to lowercase
    strupr(string1); // converts a string to uppercase
    strcat(string1, string2); // appends string2 to end of string1
    strncat(string1, string2, 1); // appends the first n characters from string2 to string1
    strcpy(string1, string2); // copies string2 to string1
    strncpy(string1, string2, 4); // copies the first n characters of string2 to replace the first n characters of string1
    
    strset(string1, '?'); // sets all characters of a string to a given character
    strnset(string1, 'x', 1); // sets the first n characters of a string to a given character
    strrev(string1); // reverses a string

    int result = strlen(string1); // returns string length as int
    int result = strcmp(string1, string2); // string compare all characters (returns 0 if equal or 1 if not equal)
    int result = strncmp(string1, string2, 1); // string compare n characters
    int result = strcmpi(string1, string1); // string compare all (ignore case)
    int result = strnicmp(string1, string1, 1); // string compare n characters (ignore case)

    printf("%s", string1);
    printf("%d", result);

    if(result == 0)
    {
        printf("These strings are the same");
    }
    else
    {
        printf("These strings are not the same");
    }
}