How to fix "expected primary-expression before 'continue'"?-CodePudding

I've started learning C and found myself in trouble with a simple problem. All that I need to do is to remove repeating spaces from stdin using a while loop, but I want to solve this problem with ternary if expressions.

Here's my code:

#include <iostream>
using namespace std;

int main()
{
    bool space = false;    // set to true if the symbol is ' '
                           // and reset to false if it's not
                           // if current symbol is ' ' 
                           // and bool is true (previous was also ' ') then
                           // I want to go to the next iteration
                           // without printing the current symbol which is repeating ' '
    char c = '\0';
    while (cin.get(c)) {
        c != ' ' ? space = false : !space ? space = true : continue;
        cout << c;
    }
    return 0;
}

And when I try to compile this code I get an error message:

expected primary-expression before 'continue'

How do I get out of this situation?

Upd: Using usual ifs is not the answer that I want because I'm not new to programming, I'm new to C . I know how to solve this with ifs, just want to try other ways.

CodePudding user response：

I assume that this obscure construction:

c != ' ' ? space = false : !space ? space = true : continue;

is meant to be this:

if(space && c == ' ') continue;
space = c == ' ';

That is, if the previous character was a space and the current is too, continue, otherwise, set space to true if the current is a space and false if it's not.

I want to solve this problem with ternary if expressions.

e1 ? e2 : e3

The result of e2 and e3 must be convertible into the same value type (see expr.cond). continue is a statement (expression). It can't be convered to bool as it should have to be in this case - so, you need to split up your expressions and put the statement where it belongs.

You can however use a throw expression like this:

    while (cin.get(c)) {
        try {
            c != ' ' ? space = false : !space ? space = true : throw 0;
            cout << c;
        } catch(...) {}
    }

... and this is exactly what exceptions should not be used for - but it "solves" your struggle with the conditional operator.