How to Pass a String in a function? - c++

Question

I have a function (int, string) in Main:
string word("HELLO");
int x = 0;
char choice;
swap(x, word);
I am trying, with no success, to pass into the following function:
void swap(int, string) {
int x = 0;
string word = "HELLO";
cout << "Would you like to change a letter? Please enter the letter
position. " << endl;
cin >> x;
if (x == 1) {
cout << "What do you want to change it to?" << endl;
cin >> word[0];
I keep getting this error:
Error C2664 'void std::swap(std::exception_ptr &,std::exception_ptr &) throw()': cannot convert argument 1 from 'int' to 'std::exception_ptr &'
What gives?

Answer 1

The main problem with your code is the indentation. Your code is not readable and mostly hard to comprehend it. Beautify it. Write nice, readable and a structured code. You can read more about indentation at the following link.
https://en.wikipedia.org/wiki/Indentation_style
The next thing is the function declaration. You do not declare your function before defining it. The function declaration should be top of the main function and definition of the function should be below the main function.
You can find more info about the function declaration at the following link:
http://en.cppreference.com/w/cpp/language/function
Since you are not using a char array to print out the string, it is useless to go through the string with a loop. Include the <string> library and start to work towards the string type. By passing the string variable inside std::cout is enough to print out the string.
Lastly, since you are trying to manipulate a string variable outside the main function, it is required that you are passing a reference parameter instead.
void myFunction(std::string& parameter);
This way, the original variable that exists inside the main or inside any other function will be altered. Without the reference, &, the value you are trying to modify will not be changed.
The following link demonstrates the use of reference.
http://www.learncpp.com/cpp-tutorial/73-passing-arguments-by-reference/
Please read my comments below of why some changes were applied. I made crafty changes to the change function. You are now eligible to work towards any
string type with any size.
#include <iostream>
#include <string> //When you are working on strings, use the string library.
using namespace std;
//Function declaration is very important. Have the declarations above main.
void change(string&);
int main() {
string word("HELLO");
char choice;
cout << "The word is : " << endl;
cout << word << endl;
//No need for the for loop to print out the string as
// we are working on a string and not a char array.
// for (int i = 0; i < word.length(); i++) {
// cout << word[i];
// }
change(word);
cout << "The new word is" << endl << word << endl;
cout << "Would you like to enter another change ? Enter Y or N ? " << endl;
cin >> choice;
if (choice == 'y' || choice == 'Y') {
change(word);
cout << word << endl;
}
else {
cout << "Good Bye" << endl;
}
system("pause");
return 0;
}
//When your datatype is to be modified outside the function, use the reference
//parameter type '&'.
//Without the reference type, your modified version of the type will only be modified
//inside that function.
//The original one will not be altered.
void change(string& word) {
/*
* size_t is simply unsigned int, to work towards manipulation and accessing
* of string types, use unsigned int or std::size_t
*/
size_t x = 0;
cout << "Would you like to change a letter? Please enter the letter position. " << endl;
cin >> x;
//Check to see if the inputted value is within the string length range.
if(x > 0 && x <= word.length())
cout << "What do you want to change it to?" << endl;
else{
cout << "The entered position is outside the string size range\n";
return; //Quit from the function if the condition is not met.
}
/*
* Instead of using if/else if statements,
* Just make a normal loop. Much simpler.
*/
for(size_t i = 0; i < word.length(); i++){
if((x-1) == i)
cin >> word[i];
}
}