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c++stringtype-conversionatoi

Convert each digit from number saved in string to array of int

I'm writing this project on DFA and i want to save and covert each digit of an integer saved as a string to an int array.This is the code from the function responsible for that:

int l=final_states.size();
int* temp_final;
temp_final=new int [l];
for(int i=0;i<l;i++)
{
    temp_final[i]=atoi(final_states.at(i).c_str());
}

This gives me the following mistake : request for member 'c_str' in '((DFA*)this)->DFA::final_states.std::basic_string<_CharT, _Traits, _Alloc>::at<char, std::char_traits<char>, std::allocator<char> >(((std::basic_string<char>::size_type)i))', which is of non-class type 'char'|.

So if you could tell me how to make this conversion and saving work , that would be great.

Solution

  • The atoi() function wants a const char*, you cannot call .c_str() with the result of .at(i) which is actually a char& value.

    Just fix your assignment line to

     temp_final[i] = int(final_states[i]) - int('0');

    Though you also might check if you really have a digit there, before putting it into your result array:

     if(std::isdigit(final_states[i])) {
     temp_final[i] = int(final_states[i]) - int('0');
 }
 else {
     // Skip, or throw error ...
 }