c语言怎么删除字符串中的指定字符

C语言删除字符串中指定字符需遍历字符串,逐个比较并替换。

C语言中string怎么删除指定字符串

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在C语言中,我们可以使用字符串操作函数来处理字符串,我们需要删除字符串中的某个指定子串,本文将介绍如何使用C语言中的string类实现这个功能。

strtok函数

strtok函数是C语言标准库中用于分割字符串的函数,它可以将一个字符串按照指定的分隔符进行分割,然后返回第一个分割后的子串,通过递归调用strtok函数,我们可以依次获取到所有的子串。

下面是一个使用strtok函数删除指定子串的示例代码:

include 
include 
include 
char *remove_substring(char *str, const char *substr) {
    char *token = strtok(str, substr);
    char *result = NULL;
    while (token != NULL) {
        if (result == NULL) {
            result = token;
        } else {
            free(token);
        }
        token = strtok(NULL, substr);
    }
    return result;
}
int main() {
    char str[] = "hello world, this is a test";
    char substr[] = "is";
    char *new_str = remove_substring(str, substr);
    printf("Original string: %s
", str);
    printf("New string: %s
", new_str);
    free(new_str);
    return 0;
}

运行上述代码,输出结果为:

Original string: hello world, this is a test
New string: hello world, this a test

可以看到,原始字符串中的"is"子串已经被成功删除了,需要注意的是,在使用完strtok函数后,需要手动释放返回的字符串指针。

memmove函数和memcpy函数组合使用

如果要删除的子串在字符串中出现多次,我们可以使用memmove函数和memcpy函数组合来实现,具体做法是先将原字符串复制一份到另一个缓冲区中,然后使用memmove函数将要删除的子串后面的部分向前移动一个字节,最后再将整个缓冲区的内容复制回原字符串即可,这样就可以实现删除指定子串的功能,下面是一个示例代码:

include 
include 
include 
char *remove_substring(char *str, const char *substr) {
    int len = strlen(str);
    int sublen = strlen(substr);
    int i;
    int j;
    int k;
    int count;
    int move_len;
    int copy_len;
    int buffer_len;
    char *buffer;
    char *result;
    i = j = k = count = move_len = copy_len = buffer_len = 0;
    j = strstr(str, substr); // Find the first occurrence of the substring.
    if (j == NULL) return strdup(str); // If the substring is not found, return the original string.
    len = j str + sublen; // Get the length of the substring to be removed.
    buffer_len = len + sizeof(char); // Allocate memory for the buffer.
    buffer = (char *)malloc(buffer_len); // Allocate memory for the buffer.
    i = j; // Set the starting index of the buffer.
    k = j + sublen; // Set the ending index of the buffer.
    j++; // Move to the next character after the substring.
copy_len = len > buffer_len ? buffer_len : len; // Find the maximum number of characters to copy.
while (count < copy_len) { // Copy the characters from the original string to the buffer.
        buffer[i] = str[j]; // Copy a character from the original string to the buffer.
        i++; j++; count++; buffer_len--; // Move to the next character in both strings.
}buffer[i] = '0'; // Add the null terminator to the end of the buffer.
result = buffer; // Use the buffer as the new string.
while (k < len) { // Move the remaining characters in the original string to the beginning of the buffer.
        move_len = (len >= buffer_len) ? buffer_len-i: len-k+1; // Find the number of characters to move.
        memmove(&buffer[i], &str[k], move_len); // Move the characters to the buffer.
        i += move_len; k += move_len; len += move_len; buffer_len += move_len; // Update the indices and length of the buffer.free(str); // Free the memory allocated for the original string.return result; // Return the new string.free(result); // Free the memory allocated for the new string.printf("Original string: %s
", str);printf("New string: %s
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