带指针的c++字符串操作，中间为null

char source[] = "Hello";
char destination[10];
strcpy(destination, source);

char str1[] = "Hello";
char str2[] = "World";
char result[20];
strcpy(result, str1);
strcat(result, str2);

char str1[] = "Hello";
char str2[] = "Hello";
int result = strcmp(str1, str2);
if (result == 0) {
    // 字符串相等
} else if (result < 0) {
    // str1小于str2
} else {
    // str1大于str2
}

char str[] = "Hello, World";
char* result = strstr(str, "World");
if (result != NULL) {
    // 子字符串存在
} else {
    // 子字符串不存在
}