How to use string in c language

A string is represented in C language as a null-terminated character array. Strings can be created through literals or using the malloc() function; characters can be accessed through the [] operator, but strings are immutable and need to be modified using functions such as strcpy(); in addition, there are multiple string manipulation functions, such as strchr () and strtok() are used to find characters and decompose strings.

Usage of string in C language

What is string?

string is a data type representing text strings in C language. It is a null character ('\0') terminated character array.

Create string

There are two main ways to create a string:

• Literal definition:

  <code class="c">char s[] = "Hello World";</code>

• Use malloc() function to allocate memory:

  <code class="c">char *s = (char *) malloc(length + 1);
  strcpy(s, "Hello World");</code>

Access characters in string

You can use the character array index operator [] to access a single character in a string:

<code class="c">printf("%c", s[0]); // 输出 'H'</code>

Modify string

string in C language is Immutable. To modify a string, you must use the following function:

• strcpy(): Copy one string to another string.
• strcat(): Concatenate two strings together.
• strlen(): Get the length of string (excluding null characters).
• strcmp(): Compare the values ​​of two strings.

String operation functions

There are other string operation functions in the C language, such as:

• strchr(): Find specific characters in string.
• strtok(): Decompose a string into substrings (tokens).
• sprintf(): Format string and write it to buffer.

Example

The following code snippet demonstrates the use of string in C language:

<code class="c">#include <stdio.h>
#include <string.h>

int main() {
    // 创建一个 string
    char s[] = "Hello World";

    // 打印 string 的长度
    printf("String length: %d\n", strlen(s));

    // 修改 string
    strcpy(s, "Goodbye World");

    // 打印修改后的 string
    printf("Modified string: %s\n", s);

    return 0;
}</code>

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