c - 读取字符串中的字符串并计算字符串1在字符串2中出现的次数

Question

我必须用 C 语言编写一个函数来计算输入字符串中字符串“mystring”的出现次数。

用户将输入一个包含短语“mystring”的字符串，字符串中任何地方都没有空格，程序将计算“mystring”在输入字符串中被读取的次数。

这是我到目前为止编写的代码，但它无法正常工作。

int substr_count(char *srcString, char *subString)
{
    int i = 0;  // counter variable
    int countOccurence = 0;   

    while(srcString[i] != 0)        // loop until hit a null in srcString
    {
        if (srcString[i] == subString[i])
        {
            countOccurence++;
        }
        i++;    // increment to next position in srcString
    }
    return countOccurence;      // return value of occurences
}

int main(void)
{
  char srcString[200] = "";  //empty string
  char subString[8] = "mystring";  //substring
  int get_count = 0;

  scanf("%s", srcString); //get a string from input keyboard

  get_count = substr_count(srcString, subString);

  printf("%s occurs %d times in %s\n", subString, get_count, srcString);
}

Answer 1

使用strstr像这样:

#include <stdio.h>
#include <string.h>

int substr_count(const char *srcString, const char *subString){
    int countOccurence = 0;
    size_t sub_len = strlen(subString);
    const char *p = srcString;

    while(p = strstr(p, subString)){//if NOT NULL, found it
        ++countOccurence;
        p += sub_len;//set next search point
    }
    return countOccurence;
}

int main(void){
    char srcString[200] = "";
    char subString[] = "mystring";//const *char subString = "mystring"
    int get_count = 0;

    scanf("%199s", srcString);//199 : Set limits
    get_count = substr_count(srcString, subString);

    printf("%s occurs %d times in %s\n", subString, get_count, srcString);
}