how to compare strings in c with code examples

In C programming, string comparison is an essential operation to evaluate whether two strings are identical or different. The comparison of two strings is generally done using some built-in functions that are provided by the standard C library.

String comparison is an operation that checks whether the two strings are identical or not. It is a crucial operation for searching, sorting, and various other programming operations. In C programming, you can compare two strings using strcmp() function, which is the most commonly used string comparison function in C programming.

The strcmp() function takes two strings as arguments and returns an integer value based on the comparison result. The function returns 0 if both strings are identical, a negative value if the first string is less than the second string, and a positive value if the first string is greater than the second string.

Syntax of strcmp():

int strcmp(const char *string1, const char *string2);

In this function, string1 and string2 are the two strings that are to be compared. The function returns the integer value based on whether both strings are identical or not.

Here's an example of how to use strcmp() function to compare two strings in C programming:

#include<stdio.h>
#include<string.h>
int main()
{
char string1[100],string2[100];
int result;
printf("Enter first string:");
scanf("%s",string1);
printf("Enter second string:");
scanf("%s",string2);
result=strcmp(string1,string2);

if(result==0)
printf("Both strings are equal");
else
printf("Both strings are not equal");
return 0;
}

In this program, we are taking two strings from the user and passing them to the strcmp() function. The function returns an integer value, which we are storing in the variable "result". If the result is equal to 0, then the strings are identical, and if the result is not equal to 0, then the strings are different.

Apart from the strcmp() function, there are also other similar string comparison functions in C programming that you can use to compare strings.

1. strncmp():

The strncmp() function is similar to the strcmp() function, but it compares only the first n characters of the two strings. This function takes three arguments: the two strings to be compared and the number of characters to be compared.

Syntax of strncmp():

int strncmp(const char *str1, const char *str2, size_t n);

Here's an example of how to use strncmp() function to compare two strings:

#include<stdio.h>
#include<string.h>
int main()
{
char string1[100],string2[100];
int n,result;
printf("Enter first string:");
scanf("%s",string1);
printf("Enter second string:");
scanf("%s",string2);
printf("Enter number of characters to be compared:");
scanf("%d",&n);
result=strncmp(string1,string2,n);

if(result==0)
printf("Both strings are equal");
else
printf("Both strings are not equal");
return 0;
}

2. strcoll():

The strcoll() function compares two strings using the current locale.

Syntax of strcoll():

int strcoll(const char *s1, const char *s2);

Here's an example of how to use strcoll() function to compare two strings:

#include<stdio.h>
#include<string.h>
int main()
{
char string1[100],string2[100];
int result;
printf("Enter first string:");
scanf("%s",string1);
printf("Enter second string:");
scanf("%s",string2);
result=strcoll(string1,string2);

if(result==0)
printf("Both strings are equal");
else
printf("Both strings are not equal");
return 0;
}

In conclusion, string comparison is an important operation in C programming that helps in evaluating whether two strings are identical or not. In order to compare two strings, C programming provides various built-in functions such as strcmp(), strncmp(), and strcoll(). With the help of these functions, you can easily compare strings in your C program.

let's dive a bit deeper into the topic of string comparisons in C programming.

One thing to note is that in C programming, strings are stored as an array of characters. The string is terminated by a special character called the null character (\0), which is added at the end of the string.

For example, if you declare a string variable in C:

char myString[] = "Hello World";

The actual contents of the string variable would be:

{'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd', '\0'}

As you can see, the null character is added at the end of the string to indicate the end of the string.

Now let's take a closer look at the strcmp() function. This function compares two strings and returns an integer value based on the comparison result. The function returns 0 if both strings are identical, a negative value if the first string is less than the second string, and a positive value if the first string is greater than the second string.

So if you have two strings:

char string1[] = "apple";
char string2[] = "orange";

When you pass these strings to the strcmp() function like this:

int comparisonResult = strcmp(string1, string2);

The comparisonResult variable will have a negative value because "apple" is alphabetically less than "orange". If the two strings were identical, the comparisonResult variable would be 0.

Another important thing to note is that when comparing two strings, the comparison is done character by character until a difference is found or the null character is reached. This means that the length of the strings being compared is important. If the strings are of different lengths, the comparison may produce unexpected results. To avoid this, you can use the strncmp() function, which compares a specified number of characters in two strings.

Hopefully, this gives you a better understanding of the basics of string comparisons in C programming. By using the strcmp(), strncmp(), and strcoll() functions, you can easily compare strings in your C program and perform various operations such as sorting and searching.

Popular questions

Sure, here are five questions about comparing strings in C programming, along with their answers.

1. What is the function used to compare two strings in C programming?
   Answer: The strcmp() function is used to compare two strings in C programming. This function takes two strings as arguments and returns an integer value based on the comparison result.

2. How is the comparison result represented by the strcmp() function?
   Answer: The comparison result is represented by an integer value returned by the strcmp() function. If the two strings are identical, the function returns 0. If the first string is less than the second string, the function returns a negative value. If the first string is greater than the second string, the function returns a positive value.

3. Can the strcmp() function compare two strings of different lengths?
   Answer: Yes, the strcmp() function can compare two strings of different lengths. However, the comparison is done character by character until a difference is found or the null character is reached. This means that the length of the strings being compared is important, and if the strings are of different lengths, the comparison may produce unexpected results.

4. What is the purpose of the strncmp() function in C programming?
   Answer: The strncmp() function is similar to the strcmp() function, but it compares only the first n characters of the two strings. This function is useful when you only want to compare a specific number of characters in two strings.

5. What is the difference between the strcmp() and strcoll() functions in C programming?
   Answer: The strcmp() function compares two strings based on their ASCII values, whereas the strcoll() function compares two strings based on the current locale. The strcoll() function is useful when you need to compare strings according to the language standards of a specific locale.

Tag

StringComparisons