主串子串操作

title: 主串子串操作date: 2020-12-5 23:50:41
tags: C++
categories: 算法

code

#include <iostream>
#include <string>
using namespace std;
//查找子串位置（0则说明查找失败）
int SearchString(int pos, char s1[], char s2[])
{//0 <= pos <= len1
    int p1 = pos - 1;
    int p2 = 0;
    int len1, len2;
    len1 = strlen(s1);
    len2 = strlen(s2);
    while (p1 < len1 && p2 < len2)
    {
        if (s1[p1] == s2[p2])
        {
            p1++; p2++;
        }
        else
        {
            p1 = p1 - p2 + 1;
            p2 = 0;
        }
        if (p2 >= len2)
            return p1 - p2 + 1;
    }
    return 0;
}
//插入子串(假设主串够大)  
void InputString(int pos, char s1[], char s2[])
{//0 <= pos <= len1+1
    int i;
    int len1 = strlen(s1);
    int len2 = strlen(s2);
    for (i = len1 - 1 + len2; i >= pos+len2; i--)
    {
        s1[i] = s1[i - len2];
    }
    for (i = 0; i < len2; i++)
    {
        s1[pos + i] = s2[i];
    }
    cout << s1;
    return;
}
//按长度删除子串
void DeleteStringOnLength(int pos,int longth,char s1[])
{
    //memset(&s1[pos],' ', sizeof(char) * longth);
    int len = strlen(s1);
    int i;
    for (i = pos;i <len - longth;i++ )
    {
        s1[i] = s1[i+longth];
    }
    memset(&s1[len-longth], 0, sizeof(char) * longth);
    cout << s1;
} 
//按子串删除子串
int DeleteStringOnSub(char s1[], char s2[])
{
    int pos = SearchString(0, s1, s2);
    if (!pos) return 0;
    else
    {
        int len1 = strlen(s1);
        int len2 = strlen(s2);
        int i;
        for (i = pos-1; i < len1 - len2; i++)  //pos与按长度删除子串的一点差别
        {
            s1[i] = s1[i + len2];
        }
        memset(&s1[len1 - len2], 0, sizeof(char) * len2);
    }
    return 1;
}
int main()
{
    int sum = 0;
    char a[30] = "abcde fc cd    cddc g";
    char b[20] = "cd";
    while (1)
    {
        if (DeleteStringOnSub(a, b))
        {
            sum++;
        }
        else
        {
            break;
        }
    }
    cout << sum << endl;
    return 0;
}