Why isn't this while loop exiting? - c++

Question

I wrote a console program to help me test a function library I coded. Part of it is this piece of code:
char insertChoice[2] = {'9'};
while (insertChoice[0] != '0')
{
cout << "\nEnter a string:\n";
char insertStringInput[256];
cin.getline(insertStringInput, 255);
char insertChoice[2];
insertChoice[0] = '9';
cout << "\nWhere would you like to insert the substring?\n\n
1) At the beginning of the string\n
2) At the end of the string\n\nInput: ";
cin >> insertChoice;
cin.ignore();
while (insertChoice[0] != '1' && insertChoice[0] != '2')
{
cout << "\nInvalid input.\nWhere would you like to insert the substring?\n\n
1) At the beginning of the string\n
2) At the end of the string\n\nInput: ";
cin >> insertChoice;
cin.ignore();
}
cout << "\nEnter the substring you would like to insert: ";
char insertSubstring[256];
cin.getline(insertSubstring, 255);
std::string used = "", substr = "";
used += insertStringInput;
substr += insertSubstring;
char insertOutputChoice[2];
insertOutputChoice[0] = '1';
if (insertChoice[0] == '1')
insertOutput(insertInBeginning(used, substr));
else
insertOutput(insertInEnd(used, substr));
cin >> insertOutputChoice;
cin.ignore();
if (insertOutputChoice[0] == '1')
{
ofstream outfile("logfile.txt", ios::app);
outfile << "Test type: Insert Substring\n";
outfile << "Test carried out on: " << __DATE__ << "; " << __TIME__ <<"\n";
outfile << "PARAMETERS:\n";
outfile << "usedString: \"" << insertStringInput << "\"\n";
outfile << "insertString: \"" << insertSubstring << "\"\n";
outfile << "function used: "
<< (insertChoice[0]=='1'?"insertInBeginning":"insertInEnd")
<< "\nOUTPUT:\n";
outfile << "\""
<< (insertChoice[0]=='1'?insertInBeginning(used, substr):insertInEnd(used, substr))
<< "\"\n\n";
outfile.close();
cout << "\nWould you like to do another string insertion test? [y/n]: ";
char insertConfirm[2];
insertConfirm[0] = ' ';
while (tolower(insertConfirm[0]) != 'y'
&& tolower(insertConfirm[0] != 'n'))
{
cin >> insertConfirm;
cin.ignore();
if (tolower(insertConfirm[0]) != 'y'
&& tolower(insertConfirm[0] != 'n'))
cout << "\nInvalid input.
Would you like to do another string insertion test? [y/n]: ";
}
if (insertConfirm[0] == 'n')
insertChoice[0] = '0';
}
}
However, the while (insertChoice[0] != '0') loop does not exit when the user types in insertOutputChoice as 1, regardless of whether the user types in insertConfirm as y or n even though it is supposed to exit when insertConfirm is typed in as n.
insertOutput looks as looks as follows:
void insertOutput(std::string substrOut)
{
cout << "\nThe new string generated is:\n";
cout << substrOut;
cout << "\n\n1) Generate a log file of this test\n";
cout << "2) Insert another substring into a string\n\n";
cout << "0) Finish testing string insertion\n\n\n";
cout << "Input: ";
}
Please excuse the messy, unoptimized code. My first priority is to get this done, and I usually leave optimization until last.

Answer 1

Inside the while loop you create a new insertChoice array. And it hides external one. So when you modify values in this array, external one remains unmodified.

Answer 2

I think there may also be an issue with the if statement at the end of the code. Have you tried this while inputting in both upper and lower case? When checking for a valid input you are converting to lowercase to check but not when checking if the response is 'n'.

Answer 3

Remove line 9:
char insertChoice[2];

Answer 4

There are a lot of errors in your code, are you sure it's compiling correctly?
First, there are 2 insertChoice declarations
char insertChoice[2] = {'9'}; // <------- 1ˢᵗ
and in the while loop:
char insertChoice[2]; // <------- 2ⁿᵈ
insertChoice[0] = '9';
The compiler should warn you about that. If not you must enable warnings with the appropriate options of your compiler (/W3 for cl, -Wall -Wpedantic for gcc...). Never compile without warnings
Second, the following string has syntax error
cout << "\nWhere would you like to insert the substring?\n\n
1) At the beginning of the string\n
2) At the end of the string\n\nInput: ";
If you want a line break in the string you must use an escape right before the new line character
cout << "\nWhere would you like to insert the substring?\n\n\
1) At the beginning of the string\n\
2) At the end of the string\n\nInput: ";
or use multiple string literals like this
cout << "\nWhere would you like to insert the substring?\n\n"
"1) At the beginning of the string\n"
"2) At the end of the string\n\nInput: ";
Consecutive literals will be automatically combined into one by the compiler
In C++-0x life is a lot easier with raw string literals where embedded quotes or newlines are possible
cout << R"(
Where would you like to insert the substring?
1) At the beginning of the string
2) At the end of the string
Input: )";