如何计算另一个字符串中字符串的出现次数 [英] How to count the occurrence of a string in another string

问题描述

你好朋友，

我尝试下面给出的代码它正常工作所有字符串（如这里是她的家试图找到他）但当我尝试anana是一个香蕉并试图找到ana这是抛出异常。请帮助我。



我尝试过：

Hello friends,
I tried below given code it is working fine with all strings(like "here is her home" trying to find "he") But when i am trying with "anana is an banana" and trying to find "ana" this is throwing exception. Please help my in this.

What I have tried:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace StringTest
{
    class Program
    {
        static void Main(string[] args)
        {          
            int count = 0, count1 = 0;
            int i, j, l1, l2; 
            Console.WriteLine("Enter a string : ");
            string str=Console.ReadLine();
            Console.WriteLine("Enter a string : ");
            string sub=Console.ReadLine(); 
            l1 = str.Length; l2 = sub.Length;
            for (i = 0; i < l1;)
            {
                j = 0;
                count = 0;                             
                    while ( (j<l2)>
                    {                        
                            count++;                        
                            i++;                      
                            j++;                        
                    }
                if (count == l2)
                {
                    count1++;                                   
                    count = 0;
                }
                else
                i++;
            }    
            Console.WriteLine("{0} occurs {1} times in {2}", sub, count1, str);
            Console.ReadLine();
       }   
   }
}

推荐答案

我在你的代码中看到了一些问题。

但我担心的是它什么也没做！

I see a few problems in your code.
But my main worry is that it does nothing !

for (i = 0; i < l1;)
{
    j = 0;
    count = 0;
        while ( (j<l2)>
        {
                count++;
                i++;
                j++;
        }
    if (count == l2)
    {
        count1++;
        count = 0;
    }
    else
    i++;
}

此代码正在使用指针和计数器，但就是这样。



使用改善问题更新你的问题。



问题：如果您输入香蕉并搜索 ana ，您应该出现多少次？

因为有两种可能性b ana na和ban ana ，但它们重叠。

This code is playing with pointers and counters, but that's all.

Use Improve question to update your question.

Question: if you have the input banana and search for ana, how many occurrences should you have ?
Be cause there is 2 possibilities banana and banana, but they overlap.

试试这个，

进行了一些更正，查看内联评论

Try this,
made some corrections, check inline comments

using System;
namespace StringTest
{
    class Program
    {
        static void Main(string[] args)
        {
            // always define the variable names more understandable. it will be easier for debugging
            int occurances = 0;
            int inputLength, findLength;
            Console.WriteLine("Enter a string : ");
            string input = Console.ReadLine();
            Console.WriteLine("Enter a string to find : ");
            string find = Console.ReadLine();
            inputLength = input.Length; findLength = find.Length;

            // if you have only one line of code, next to 'for' and 'if' statements, its not mandatory to use '{','}' brackets as below.

            for (int i = 0; i < inputLength; i++)  // loop each character from the input string
                if (inputLength >= i + findLength)  // check the input length is greater than equal to loop index + find key length (validation, to avoid index exception in the next line )
                    if (find == input.Substring(i, findLength))  // match the finding key with the current instance (index + key length)
                        occurances++; // if the condition satisfies , do increament 


            Console.WriteLine("'{0}' occurs {1} times in '{2}'", find, occurances, input);
            Console.ReadLine();
        }
    }
}

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