Why isn't atoi() working for me?

[Jgrabow1]

instructionRegister is a private member string variable in my Simpletron class.
It will always look something like this: +21007

void Simpletron::decode()
{
	string operandTemp;
	string opCodeTemp;

	opCodeTemp[0] = instructionRegister[1];
	opCodeTemp[1] = instructionRegister[2];

	operandTemp[0] = instructionRegister[3];
	operandTemp[1] = instructionRegister[4];
	operandTemp[2] = instructionRegister[5];

	operationCode = atoi(opCodeTemp);
	operand = atoi(operandTemp);
}

Error message reads: simpletron.cpp(29) : error C2664: 'atoi' : cannot convert parameter 1 from 'std::string' to 'const char *'
1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

Anyone know why?

~James

[dearvivekkumar]

Make this changes. As atoi is expecting "const char*" type and you have given string type.

operationCode = atoi(opCodeTemp.c_str());
operand = atoi(operandTemp.c_str());

[Shinigami]

And what type are variables operationCode and operand?