[C++] String ptr with c_str

[xnerdx]

I'm having an issue with a function I built to make the string all lower case. I have the fucntion taking an argument of (string* uInput) and the function is called by (&tempInput). In the function being called I'm trying to run uInput.c_str() (I've also tried c_str(uInput) but I get an error about c_str() being undeclared (first use in function). Here is the class function I'm attempting to build:


void FCard::makeAllLower(string* uInput)
{
for(int i = 0; i < strlen(c_str(uInput)); i++)
{
uInput[i] = tolower(uInput[i]);
}
}

I use c_str in other instances of the program and have no problem. Is it because I'm using a string*?

[dwhitney67]

Use uInput.size() or uInput.length() to acquire the size of the string.

Or do something like:


void FCard::makeAllLower(std::string& uInput)
{
for (std::string::iterator it = uInput.begin(); it != uInput.end(); ++it)
{
*it = tolower(*it);
}
}

I recommend that you pass class objects by reference, not by pointer. This is typically what is done; but do what you want.


P.S. Another alternative:


void myToLower(char& ch)
{
ch = tolower(ch);
}

void FCard::makeAllLower(std::string& uInput)
{
std::for_each(uInput.begin(), uInput.end(), myToLower);
}

[xnerdx]

I made the mistake of thinking that to pass by reference I had to pass the arguements to (string& uInput) with (*tempInput). Simply changed it to (tempInput) and compiled fine :D