Question

So, I try to use atoi function to convert a string to int, however I got an error saying that argument type char is incompatible with parameter of type const char*. here is the code:

void evaluate(const char values[], string& codeMessage, string& result)
{
    unsigned int i = 0;
    while (i<codeMessage.length())
    {
        result+= values[atoi(codeMessage[i])];
        i++;
    }
}

so, if the function evaluate({a,b,c,d}, "2331", result) is called, the result have to contain "cdda". any idea, what’s wrong w/ my code? thx

Answer 1

atoi expects a C-string, not a single character.

If you want to lexically convert a digit to the equivalent integer, why not simply assert that it’s between '0' and '9', then subtract '0'? Numbers are required to be consecutive regardless of the locale’s character set.

while (i < codeMessage.length()) {
    if (codeMessage[i] >= '0' && codeMessage[i] <= '9') {
       result += values[codeMessage[i] - '0'];
    }

    i++;
}