How to Compare Two Strings in C Programming

There are two functions that allow you to compare strings in C. Both of these functions are included in the library. strcmp() - This function compares two strings and returns the comparative difference in the number of characters. strncmp() - This is the same as strcmp(), except that it compares the first n characters. It is considered more secure as it helps prevent crashes from overflow.

Start the program with your necessary libraries. You'll want both the and libraries, along with any others you may need for your specific program. #include #include

Start an .int function. This is the easiest way to learn this function, as it will return an integer that compares the length of the two strings. #include #include int main () { }

Define the two strings you want to compare. For this example, we will be comparing two predefined char strings. You will also want to define the return value as an integer. #include #include int main () { char *str1 = "apple"; char *str2 = "orange"; int ret; }

Add the comparison function. Now that you have your two strings defined, you can add the comparison function. We are going to use strncmp(), so we need to ensure that the number of characters to be measured is set in the function. #include #include int main () { char *str1 = "apple"; char *str2 = "orange"; int ret; ret = strncmp(str1, str2, 6); /*This will compare the two strings up to 6 characters long */ }

Use an .If...Else statement to perform the comparison. Now that you have the function in place, you can use an If...Else statement to display which string is longer. strncmp() will return 0 if the strings are the same length, a positive number if str1 is larger, and a negative number if str2 is larger. #include #include int main () { char *str1 = "apple"; char *str2 = "orange"; int ret; ret = strncmp(str1, str2, 6); if(ret > 0) { printf("str1 is longer"); } else if(ret < 0) { printf("str2 is longer"); } else { printf("The two strings are equal"); } return(0); }