c++ - 如何在另一个字符串的x位置插入一个字符串？

Question

我必须使用一个接受两个字符串和一个整数值的函数，该值指示在第一个字符串中输入第二个字符串的位置。

例如:

String 1 = "I have apple"
String 2 = "an " 
position = 6, 

输出:

String 1 = "I have an apple"

到目前为止，这是我的代码:

#include <iostream>
using namespace std;

const int SIZE=102;

void insertString(char str1[ ],char str2[ ],int position);

int main()
{
    char str1[SIZE], str2[SIZE];
    int position,i=0,j=0;

    cout<<"Enter string 1 of atmost 50 characters:\n";
    cin.getline(str1,SIZE/2);

    cout<<"Enter string 2 of atmost 50 characters:\n";
    cin.getline(str2,SIZE/2);

    cout<<"Enter Position number where String 2 is to be inserted: ";
    cin>>position;

    while(position<0||position>50)
    {
        cout<<"Invalid input. Enter a positive Position number less than 51\n"<<
        "where String 2 is to be inserted: ";
        cin>>position;
    }

    insertString(str1,str2,position);

    cout<<"Modified string 1: "<<str1<<endl;

    system("pause");
    return 0;
}

/******************************************************************************
Definition of function insertString:

This function takes two C-string in form of character arrays and one integer value
as parameters

It inserts String 2 in String 1 on the required position. 

*******************************************************************************/

void insertString(char str1[ ],char str2[ ],int position)
{
    char temp[SIZE]; 
    int i,j,countStr2;

    for(j=0;j<SIZE&&str2[j]!=0;j++)
        countStr2=j;

    for(i=position,j=0;i<SIZE,j<=countStr2; i++,j++)
    {
        temp[i]=str1[i];
        str1[i]=str2[j];

    }

}

此逻辑将覆盖字符串1的某些字符。我该怎么办？

任何帮助将不胜感激。

Answer 1

#include<cstring>
#include <iostream>
/*The following function supposes that str1 and str2 are cString (i.e)
ended by `\0` and inserts str2 in str1 at the specified position in a
newStr, then returns the new string as apointer*/

char* insertString(const char str1[ ],const char str2[ ],const int& position)
{
    int shiftedPos=position-1;
    int str2Size=strlen(str2);
    int str1Size=strlen(str1);
    int newSize=str2Size+str1Size+1;

    char* newStr=new char[newSize];
    for(int i=0; i<shiftedPos; i++) newStr[i]=str1[i];

    for(int i=0; i<str2Size; i++) newStr[shiftedPos+i]=str2[i];
    for(int i=0; i<newSize; i++) newStr[shiftedPos+str2Size+i]=str1[shiftedPos+i];

    newStr[newSize]='\0';

    return newStr;
}
int main(){
    auto str1 = "I have apple";
    auto str2 = "an ";
    std::cout<<insertString(str1,str2, 8);
    return 0;
}

另一个代码可以完全按照您的要求执行

#include<iostream>
#include<cstring>
/*The following function supposes that str1 and str2 are cString (i.e)
ended by `\0` and that the memory allocated by str1 >= the len(str1)+len(str2)+1.
It inserts str2 in str1 at the specified position in str1*/

void insertString(char str1[ ], char str2[ ], int position)
{
    int str1Size=strlen(str1);
    int str2Size=strlen(str2);
    int newSize=str2Size+str1Size+1;
    int cppPosition=position-1;

    for(int i=str1Size; i>=cppPosition; i--) str1[i+str2Size]=str1[i];
    for(int i=0; i<str2Size; i++) str1[cppPosition+i]=str2[i];
    str1[newSize]='\0';
}
int main(){
    char str1[50]= "I have apple";
    char str2[50] = "an ";
    insertString(str1,str2, 8);
    std::cout<<str1;
    return 0;
}