C++ , experience problems to convert double to int

Question

Need the code bellow to accept values in double and convert in int

using namespace std;

SymbolTable symbolTable;

void parseAssignments();

int main()

{

    Expression* expression;

    char paren, comma;

    cout << "Enter expression: ";

    cin >> paren;

    expression = SubExpression::parse();

    cin >> comma;

    parseAssignments();

    cout << "Value = " << expression->evaluate() << endl; 

    return 0;

}

void parseAssignments()

{

    char assignop, delimiter;

    string variable;
    double value;

    do

    {

        variable = parseName();

        cin >> ws >> assignop >> value >> delimiter;

        symbolTable.insert(variable, value);

    }

    while (delimiter == ',');

}

Why you are accepting double and string to int type? Provided code not give complete picture. — Build Succeeded, Dec 11 '19 at 05:01
It seems that the problem is just with the conversion of `value` from `double` to `int`. Strip away the extraneous code and focus on the problem. — Raymond Chen, Dec 11 '19 at 07:00

score 0 · Answer 1 · answered Dec 11 '19 at 07:30

A quick way to convert from double to int is to set an int equal to a double. The int will store the truncated value, meaning it does not round after the decimal, merely ignores it. For example:

double pi = 3.14;
int piApprox = pi;

cout<<pi<<endl; // This will output 3.14
cout<<piApprox<<endl; //This will output 3

Hope this helps, your questions is very similar to this post here. That one goes into more detail about the engineering aspects of how floating point numbers work in computers and precautions in converting from float to int.

C++ , experience problems to convert double to int

1 Answers1