I was trying to convert String into ASCII value using Recursive function. By using the string only a-CodePudding

This is my code (I want to use string as the parameter only):

#include <iostream>
using namespace std;

int i = 0;      //to take string character by character

void parseToInteger (string s1)
{
    char convert;
    string another;
    if (convert == s1.length())     //at null character function terminates
    {
        cout<<endl;                 // prints nothing
    }
    else
    {
        convert = s1.at(i  );
        static_cast <int> (convert);
        cout<<convert;
        parseToInteger (s1); 
    }
    
}

int main ()
{
    string s0;
    cout<<"Enter a string to convert it into its integer value: ";
    getline (cin, s0);
    parseToInteger (s0);
    return 0;
    
}

This is the error I am getting:

Enter a string to convert it into its integer value: hello
terminate called after throwing an instance of 'std::out_of_range'
  what():  basic_string::at: __n (which is 32540) >= this->size() (which is 5)

Can someone please help me? I am learning to program.

CodePudding user response：

Your if (convert == s1.length()) is very strange. That expression is comparing an uninitialized char variable to the length of the s1 string (which will be of size_t type). What you should be doing is comparing the i variable to the length (and that i would be better defined as size_t type).

Also the static_cast <int> (convert); line does nothing. You can't change the type of a variable like that; instead, you should use the cast on the operand of the cout << in the following line. And note that, when casting a character digit to its integer value, you need to subtract the value of '0' from it.

Here's a fixed version that addresses the above issues:

#include <iostream>
#include <string> // You 'forgot' this required header

size_t i = 0; // The "size_t" type is better suited for container sizes and lengths

void parseToInteger(std::string s1)
{
    char convert;
//  std::string another; // Never used!
    if (i == s1.length()) { // Here, we've reached the end of the string
        std::cout << std::endl;                 // prints nothing
    }
    else {
        convert = s1.at(i  );
        std::cout << cout << static_cast <int> (convert - '0'); // Apply the cast here
        parseToInteger(s1);
    }
}

int main()
{
    std::string s0;
    std::cout << "Enter a string to convert it into its integer value: ";
    std::getline(std::cin, s0);
    parseToInteger(s0);
    return 0;
}

But note, there are other concerns in your code, as mentioned in the comments. First, it would be better to pass the s1 argument by reference; second: Are global variables bad?

Here's a version of your function that addresses these last two concerns:

void parseToInteger(std::string& s1, size_t i = 0)
{
    if (i == s1.length()) { // Here, we've reached the end of the string
        std::cout << std::endl;        // 'flushes' output stream
    }
    else {
        char convert = s1.at(i  );
        std::cout << static_cast <int> (convert - '0'); // Convert to int
        parseToInteger(s1, i);
    }
}

The default value (of zero) for the new i argument means that you don't have to change the call in the main function.