Basic issue related to strings & compiler error.

[Radius]

Greetings!

I am basically new to C++. After being quite adept at Applesoft BASIC & Pascal, back in the day, it is frustrating for me to seem so clueless. I do clearly understand the difference between high & low level languages, but its still frustrating.

This is for a class I am taking at SFSU, and I have tried everything under the sun that I can see, or think, to try, and yet... I feel that it is staring me in the face, but I have looked at the code for to long, and am not seeing it. Which is why I am asking for help from the larger community. Here is the very simple code, part of the larger program, that when I resolve the issues here, I will understand how to apply them overall (hopefully).

#include <iostream>
#include <string>

using namespace std;

int main(void)
{
string monthNum;
string dateNum;
string month;
string day;
int nineTeen = 19;
string tens;
string year;

cout << "\n\nPlease enter a date in the format MM/DD/YY: ";
cin >> dateNum;

tens = dateNum.substr(6,2);
day = dateNum.substr(3,2);
monthNum = dateNum.substr(0,2);

{
if (monthNum = "01" )
month = "Janurary";
else
if (monthNum = "02" )
strcpy(month, "Feruary");
else
if (strcmp(monthNum, "03")) = 0)
strcpy(month, "March");

Just after the line containing the first "if", I am getting an error stating "Could not convert monthNum. sd::basic_string..." The other "if" statements, and subsequent, are giving me similar issues. The above three "if" evaluations are the various forms I have tried, to no avail.

Would very much appreciate a bit of guidance, not a complete answer, mind, but just a slap upside the head as to what I am missing/not seeing.

Thanks much!
Ray~

[helios]

C++ is still high-level, but it is lower-level than things like BASIC or Pascal.

MM/DD/YY

And I thought this had been out-grown.

if (monthNum = "01")

You must mean

if (monthNum == "01")

Common newbie error.

strcmp(monthNum, "03"))

std::string already has a comparison method. The operator==. You don't need to use strcmp(), but if you really want to, you're doing it wrong:

if (strcmp(monthNum.c_str(), "03")) == 0){
	//...
}

std::string::c_str() returns a pointer to the internal C string. You can't assign a value to the return value of a function.

[qoute]strcpy(month, "March");[/quote]You can't use any of the C library functions directly on an std::string, but it's not wise to mix C++ types with C functions, anyway.

[firedraco]

In C++ the logical equality operator is '==' not '='. Btw, don't use strcmp() for strings, just use the == like you were doing.

[Radius]

helios & firedraco, I thank you very much for the clarification. As I expected, it was something I knew, but had not completely assimilated, and when I went over the code... my brain was flat lining. Quickly got rid of the rubble, and it complied fine. Again, my thanks.

One follow up question, if I may. Same bit of code, but do you see any reason the program would hang/stop following the "cin >>"?

#include <iostream>
#include <string>

using namespace std;

int main(void)
{
string monthNum;
string dateNum;
string month;
string day;
int nineTeen = 19;
string tens;
string year;

cout << "\n\nPlease enter a date in the format MM/DD/YY: ";
cin >> dateNum;

tens = dateNum.substr(6,2);
day = dateNum.substr(3,2);
monthNum = dateNum.substr(0,2);

{

Best!
Ray~

[firedraco]

It's because it is waiting for input from the user (typing into the console).

[Radius]

No, perhaps I miss stated that. I meant the hang occurred after the user had input the date, and pressed return. I found the problem; apparently, it does not accept the "Enter" key as indicating you are finished with your input. I must use the "Return" key, and then it works fine.

Thanks again!
Ray~

[firedraco]

It might be because the return key is sending a \r, and cin wants a \n (enter might send \n or \r\n, I don't know). Don't quote me on this though...I don't have a return key on my keyboard.