C Language String Handling Techniques: How to Efficiently Operate on Character Arrays

In C language, strings are stored as character arrays. Although C does not have a built-in string type, we can efficiently handle strings using character arrays and some standard library functions. This article will introduce some commonly used string handling techniques and provide corresponding code examples.

1. String Definition and Initialization

In C language, strings can be defined and initialized using character arrays. Here is a simple example:

#include <stdio.h>
int main() {    char str1[] = "Hello, World!"; // Initialized using double quotes    char str2[20]; // Define a sufficiently large character array
    // Manual assignment    for (int i = 0; i < 13; i++) {        str2[i] = str1[i];    }    str2[13] = '\0'; // Add null terminator
    printf("%s\n", str2); // Output: Hello, World!
    return 0;}

Explanation:

• <span>char str1[]</span> is a method of direct initialization using double quotes.
• <span>char str2[20]</span> defines a character array of length 20, which can accommodate longer strings.
• Strings must end with a null character (<span>\0</span>) to indicate termination.

2. String Length Calculation

To obtain the length of a string, you can use the <span>strlen()</span> function, which is located in the <span><string.h></span> library.

#include <stdio.h>
#include <string.h>
int main() {    char str[] = "Hello, World!";
    size_t length = strlen(str);
    printf("The length of the string is: %zu\n", length); // Output: The length of the string is: 13
    return 0;}

Explanation:

• <span>strlen()</span> function returns the actual length excluding the null character.

3. String Copying and Concatenation

We can use <span>strcpy()</span> and <span>strcat()</span> to copy and concatenate strings.

#include <stdio.h>
#include <string.h>
int main() {    char source[] = "Hello";    char destination[20];
    strcpy(destination, source); // String copy    strcat(destination, ", World!"); // String concatenation
    printf("%s\n", destination); // Output: Hello, World!
   return 0;}

Explanation:

• <span>strcpy(destination, source)</span> copies the source string to the destination.
• <span>strcat(destination, ", World!")</span> appends new content to the end of the destination string.

4. String Comparison

To compare whether two strings are equal, you can use the <span>strcmp()</span> function:

#include <stdio.h>
#include <string.h>
int main() {   char str1[] = "apple";   char str2[] = "banana";
   int result = strcmp(str1, str2);
   if (result == 0) {       printf("Strings are equal.\n");   } else if (result > 0) {       printf("'%s' is greater than '%s'.\n", str1, str2);   } else {       printf("'%s' is less than '%s'.\n", str1, str2);   }
   return 0;}

Explanation:

• <span>strcmp(str1, str2)</span> returns zero if the two strings are equal, greater than zero if the first is greater than the second, and less than zero otherwise.

5. Substring Search

To find the position of a substring, you can use the <span>strstr()</span> function:

#include <stdio.h>
#include <string.h>
int main() {   char haystack[] = "This is a simple example.";   char needle[] = "simple";
   char *position = strstr(haystack, needle);
   if (position != NULL) {       printf("Found substring at position: %ld\n", position - haystack);   } else {       printf("Substring not found.\n");   }
   return 0;}

Explanation:

• If the substring is found, <span>strstr(haystack, needle)</span> returns a pointer to the first occurrence; otherwise, it returns NULL.

Conclusion

The above are some basic yet practical string handling techniques in C language. These methods can help you operate and manage character arrays more effectively. Mastering this foundational knowledge is crucial for writing efficient and maintainable code in actual development. I hope this article is helpful to you.