Manipulating strings

[nmenumero1]

I have to take a name from Last, First Middle and display it as First Middle Initial and Last Name without commas. Can someone tell me where my code is wrong or better explain how to use the 'find' command to make the following code work?

/******************************************************************************
 * stringProg.cpp
 * 
 *
 * Program string myString and manipulation of the string.
 ******************************************************************************/
 
 #include <iostream>
 #include <string>
 
using namespace std;

void inputData(string & myString);
void outputData(string myString);


int main()
{
	string myString;
	inputData(myString);
	outputData(myString);
	return 0;
}

void inputData(string & myString)
{
	cout << "Please type your full name in the following format:" << endl;
	cout << "Last, First Middle  -- Note there is no comma between First and Middle" << endl;
	string first, middle, last;
	getline(cin, myString);
	
	int index = myString.find(",", 0);
	last = myString.substr(0, index); //get last name and then erase that part
	myString.erase(0, index + 1);     //of the string up to the index
	
	index = myString.find(" ", 0);
	first = myString.substr(0, index);//get first starting with space after comma
	myString.erase(0, index + 1);     //and erase that plus one
	
	index = myString.find(" ", 0);
	middle = myString.substr(0, index);//use what is left of myString and take
	myString.erase(0, index + 2);      //just the first character
	
	myString += first + " ";
	myString += middle + " ";//myString adding each part of the name together
	myString += last;
	
	myString.insert(first.length() + middle.length() + 1, " " + last.substr(0,1));
	
}

void outputData(string myString)
{
	cout<< myString << endl;
	system("pause");
	

}

[wolle]

Can someone tell me where my code is wrong or better explain how to use the 'find' command to make the following code work?

You're making a newbie mistake and that's to first produce a pile of code and then try to make it work. Instead use a technique called Stepwise Refinement. Enter code in small steps and make sure it works as intended after each step before you continue with the next.

In this case first "comment out" everything in inputData after the getline statement. Then put in a print statement so you are sure myString holds what you expect.

Then "comment in" the first manipulation of myString and make sure the result is the expected by printing it so you know for sure your code works fine so far. Then repeat this process one string manipulation at a time until you reach the wanted result.

There's more to Stepwise Refinement than this but this is a start.

[2kaud]

... and also learn how to use the debugger to trace through code, watch variables etc and 'see' what is happening in the code.

Note that .find() takes as a second parameter the starting index for the search - which defaults to 0. So in your first .find(), there is no need to specify 0. Also, there is no need to erase parts from mystring - use the result of the previous find as the second parameter for the next .find() (with an appropriate adjustment) and adjust the starting position for .substr() accordingly. Also note that there is a space after the , so the search for the space separating first from middle needs to start after that. So you only need 2 finds - one to find the , and one to find the ' ' between first and middle with .substr() used to obtain the 3 parts which can then be concatenated together to produce the required string. .insert() isn't needed as the concatenation itself will produce mystring. .find() returns a type of size_t and not int. So the type of index should be size_t - or even better auto.

auto index = myString.find(",");

Also note that outputdata() should take mystring as a const reference - not by value which causes an un-neccessary copy to be made.

This assumes that there is only one space between , and first and one space between first and middle. If more than one space is allowed that additional steps will be needed to deal with that.

For info on .find() see http://www.cplusplus.com/reference/string/string/find/

PS As inputData() returns a string, why have it as a function parameter - why not just have it as the function return value? Modern c++ doesn't do a by-value return copy of the returned data - so there is now no performance impact.

[nmenumero1]

You're making a newbie mistake and that's to first produce a pile of code and then try to make it work. Instead use a technique called Stepwise Refinement. Enter code in small steps and make sure it works as intended after each step before you continue with the next.

In this case first "comment out" everything in inputData after the getline statement. Then put in a print statement so you are sure myString holds what you expect.

Then "comment in" the first manipulation of myString and make sure the result is the expected by printing it so you know for sure your code works fine so far. Then repeat this process one string manipulation at a time until you reach the wanted result.

There's more to Stepwise Refinement than this but this is a start.

This is sound advice. Thank you. I did finally figure out how to make my code work. Here's how it turned out.

#include <iostream>
#include <string>

using namespace std;

void inputData(string & myString);
void outputData(string myString);


int main()
{
    string myString;
    inputData(myString);
    outputData(myString);
    return 0;
}

void inputData(string & myString)
{
    cout << "Please type your full name in the following format:" << endl;
    cout << "Last, First Middle  -- Note there is no comma between First and Middle" << endl;
    string first, middle, last;
    getline(cin, myString);    
    
    int index = myString.find(',', 0);
    last = myString.substr(0, index); //get last name and then erase that part
    myString.erase(0, index + 1);    //of the string up to the index
    
    while (myString[0]==' ') myString.erase(0, 1);    //erase left 
 
    index = myString.find(' ' , 0);
    first = myString.substr(0, index);//get first starting with space after comma
    myString.erase(0, index + 1);    //and erase that plus one
    while (myString[0]==' ') myString.erase(0, 1);    //erase left      
    
    middle=myString.substr(0, 1); //get middle initial
    myString.erase(0,myString.length());//make it empty
    myString+=first+" "+middle+" "+last;//create myString as first middle last 
   
    myString.insert(first.length()+2,".");  //insert period after middle initial
    
   //this assignment was a big headache ... glad it finally works
}

void outputData(string myString)
{
    cout<< myString << endl;
    system("pause");
   

}

[2kaud]

//this assignment was a big headache ... glad it finally works

yes great - but the code could be simplified.

If you assume only 1 space before/after first name then consider

void inputData(string& myString)
{
	cout << "Please type your full name in the following format:" << endl;
	cout << "Last, First Middle  -- Note there is no comma between First and Middle" << endl;

	getline(cin, myString);

	const auto indl = myString.find(',');
	const auto indf = myString.find(' ', indl + 2);
	myString =  myString.substr(indl + 2, indf - indl - 2) + " "s + myString[indf + 1] + ". "s + myString.substr(0, indl);
}

but if assume that there may be multiple spaces before the surname and multiple spaces before/after the first name, then consider

void inputData1(string& myString)
{
	cout << "Please type your full name in the following format:" << endl;
	cout << "Last, First Middle  -- Note there is no comma between First and Middle" << endl;

	getline(cin, myString);

	const auto ind0 = myString.find_first_not_of(' ');
	const auto indl = myString.find(',', ind0);
	const auto ind = myString.find_first_not_of(' ', indl + 1);
	const auto indf = myString.find(' ', ind + 1);
	const auto ind1 = myString.find_first_not_of(' ', indf + 1);

	myString = myString.substr(ind, indf - ind) + " "s + myString[ind1] + ". "s + myString.substr(ind0, indl - ind0);
}