CODEWITHSUNDEEP
c++
R Bowen
R Bowen

Reputation: 67

Convert char to int?

I'm making a battleships game, so when I pass something such as "A10" into the coordinate function it needs to make column into letter and row into the number.

Coordinate(std::string coord = "A10")
    {
        char c = coord[0];
        col = c - 16;

        int r = atoi((coord.substr(1,2)).c_str());
        row = r-1;
    };

So in this example, passing A10 should make col = 0 (A=0,B=1,C=2) and row = 9.

The row equaling 9 seems to work but col equally 0 does not.

Upvotes: 0

Views: 621

Answers (4)

chrisvarnz
chrisvarnz

Reputation: 457

The decimal value for A (0x41) is 65, so you'd get 49 with your current maths. col = c - 65 should give you the desired behaviour.

Upvotes: 0

qdii
qdii

Reputation: 12953

What you call character 'A' is just a funny name for the number 65 (its ASCII value). According to this ASCII table, 'B' = 66, 'C' = 67 and so on. So what you should do is compute int column = static_cast<int>(coord[0] - 'A').

Upvotes: 0

Ben Cottrell
Ben Cottrell

Reputation: 6110

Are you trying to map the value of 'A' to zero? Remember that characters are single-byte integers, 

char c = std::toupper( coord[0] );
if( c >= 'A' && c <= 'Z' )
{
    col = c - 'A';
}
else
{
    // TODO: Invalid/error?
}

Upvotes: 2

Asha
Asha

Reputation: 11232

It should be col = c - 'A' to get the integer for A.

Upvotes: 8

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