Strcmp function in C programming
In the world of C programming, where strings form a fundamental part of data manipulation and communication, understanding how to compare these strings is essential. This is where the `strcmp` function, a key component of the C standard library, becomes particularly important. This introduction aims to shed light on the `strcmp` function, exploring its purpose, functionality, and practical applications in C programming.
What is `strcmp`?
The `strcmp` function, short for string compare, is a standard library function in C, defined in the `string.h` header file. It’s used for comparing two strings lexically (character by character). This function plays a crucial role in various applications where string manipulation and comparison are necessary, such as sorting arrays of strings, searching for strings within arrays, and checking user input.
How does the `strcmp` function work?
The `strcmp` function compares two strings character by character using the ASCII value of the characters. It starts with the first character of each string and continues to the next pair of characters until it finds a pair that differs or reaches the end of a string.
The comparison is done as follows:
1. The ASCII value of the first character of the first string (`str1`) is compared with the first character of the second string (`str2`).
2. If the characters are equal, `strcmp` moves to the next pair of characters.
3. This process continues until characters that do not match are found or until a null character ` ` (signifying the end of a string) is reached.
What does `strcmp` return?
The return value of `strcmp` provides an indication of the lexical relation between the two strings:
0: This is returned if the two strings are equal.
Negative value: If the first non-matching character in `str1` has a lower ASCII value than the corresponding character in `str2`.
Positive value: If the first non-matching character in `str1` has a higher ASCII value than the corresponding character in `str2`.
It’s important to note that the actual numeric value of the positive or negative return is not standardized and may vary between different C implementations.
`strcmp` – example
Let’s look at a simple example to demonstrate the use of `strcmp`:
#include
#include
int main() {
char string1[] = “Hello”;
char string2[] = “World”;
char string3[] = “Hello”;
int result;
// Comparing string1 and string2
result = strcmp(string1, string2);
if (result == 0) {
printf(“String1 and String2 are equal.n”);
} else {
printf(“String1 and String2 are different.n”);
}
// Comparing string1 and string3
result = strcmp(string1, string3);
if (result == 0) {
printf(“String1 and String3 are equal.n”);
} else {
printf(“String1 and String3 are different.n”);
}
return 0;
}
In this example, `strcmp` is used to compare `string1` with `string2` and `string1` with `string3`. The first comparison will return a non-zero value indicating that “Hello” and “World” are different, while the second comparison will return 0, indicating that the two instances of “Hello” are equal.
Conclusion
Understanding and using the `strcmp` function is essential for efficiently handling strings in C. It provides a standardized and straightforward way to compare strings, a task that is common in many programming scenarios.
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