I get a conversion error from char* to char when I try and compile my code

Question

I've cut out a lot of the code to make it easier to read. Specifically I'm trying to rewrite strcat

#include <iostream>
using namespace std;

char MYstrcat(char string1[],char string2[]);

int main()
{
    char letter, letter_ans, again;
    const int SIZE = 80;
    char string1 [SIZE];
    char string2 [SIZE];

getting input for the character arrays

    cout << "Enter the first string: ";
    cin >> string1;
    cout << "Enter the second string: ";
    cin >> string2;
    letter_ans=MYstrcat(string1, string2);
    cout << letter_ans;

    cin.get(); cin.get();
    return 0;
}

this is my version of the strcat function

char MYstrcat(char string1[],char string2[])
{ 
    int i = 0; //Counters
    int j = 0;

    //Read until null character is encountered then append.
    while (string1[i] != '\0')
    {
        i++;
    }
    while (string2[j]!= '\0'){
        string1[i] = string2[j];
        i++;
        j++;
    }
    string1[i]='\0'; // Place a null character in string2.

i get the error in this next line: invalid conversion from 'char*' to 'char'

    return string1;
}

Note the wrong comment in `string1[i]='\0'; // Place a null character in string2` — Sjoerd, May 03 '12 at 04:23
You should probably avoid raw arrays in C++ : http://stackoverflow.com/a/10253277/365496 — bames53, May 03 '12 at 04:45

score 3 · Accepted Answer · answered May 03 '12 at 04:28

3

char MYstrcat(char string1[],char string2[]); // returns a single character
char *MYstrcat(char string1[],char string2[]); // returns a pointer to a string that can be used like string1[] and string2[]

Likewise,

char letter_ans;    // this gives space for a single char, like int int_ans;
char *letter_ans;   // this makes a pointer to an array of char's, the proper return type

However, since you are returning string1, it may be possible that you don't even want to use a return type. If you declare your function as so:

void MYstrcat(char *string1,char *string2);

It will operate directly on string1, leaving no need to return a pointer to it.

answered May 03 '12 at 04:28

std''OrgnlDave

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Thanks a lot! That explanation was very helpful and my code now works. I got it to work as a void function before, but I wanted it to return a value in case I wanted to do more things to the returned value. – ceeplusplus May 03 '12 at 05:09
@ceeplusplus if you like the answer, don't forget to click the check mark! :-P thanks – std''OrgnlDave May 03 '12 at 05:15

score 2 · Answer 2 · answered May 03 '12 at 04:22

2

Arrays decompose in to pointers in C++, so when you do return String1 you are returning a char*, hence the return type of your function should be char*.

answered May 03 '12 at 04:22

Naveen

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+0.50000004 for right answer, +0.49999996 for "decompose" = +1 (or about that) – chris May 03 '12 at 04:25
-0.000001 for lack of content. not that I down-voted but put a little effort into it eh? :-P – std''OrgnlDave May 03 '12 at 04:29

score 1 · Answer 3 · answered May 03 '12 at 04:20

1

You're returning a char in your header, not a string.

answered May 03 '12 at 04:20

chris

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I'm not sure if I follow. I want the function to return a character array instead of a string. I just tried changing the prototype & header to `string MYstrcat(char string1[],char string2[]) but that gave me a different error in my function call: cannot convert 'std::string' to 'char' in assignment| – ceeplusplus May 03 '12 at 04:29
@ceeplusplus, Without using `std::string`, you'd have to change it to `char *`, but make sure that you're not returning a pointer to something that will be destructed once your function ends. – chris May 03 '12 at 04:31

score 1 · Answer 4 · edited May 03 '12 at 15:26

1

The function header char MYstrcat(char string1[],char string2[]); declares the return type as char, but the function body is returning a string. return string1;

edited May 03 '12 at 15:26

octopusgrabbus

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answered May 03 '12 at 04:25

Nikson Kanti Paul

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score 0 · Answer 5 · edited May 03 '12 at 14:05

0

because string1 is an char array. ie:char[]... but your function's return type is char . so you got an error.you can change you function's return type to char*, then test your code. good luck.

edited May 03 '12 at 14:05

Suchi

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answered May 03 '12 at 09:12

Rollen Holt

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I get a conversion error from char* to char when I try and compile my code

5 Answers5