I'm getting error expected primary-expression before '=' for my for loop

Question

#include <bits/stdc++.h>
using namespace std;
void SieveOfEratosthenes(int num)
{
    bool pno[num + 1];
    memset(pno, true, sizeof(pno));
    for (int i = 2; i* i < = num; i++)
    {
        if (pno[i] == true)
        {
            for (int j = i * 2; j < = num; j + = i)
                pno[j] = false;
        }
    }
    for (int i = 2; i < = num; i++)
        if (pno[i])
            cout << i << " ";
}
int main()
{
    int num = 15;
    cout << "The prime numbers smaller or equal to " << num << " are: ";
    SieveOfEratosthenes(num);
    return 0;
}

the error is in the for loop. According to me the code is correct.

`j< = num` -> `j <= num` (in all cases). C++ ignores most whitespace, but you cannot separate symbols in an operator. — Yksisarvinen, Aug 05 '20 at 10:45
You should avoid using [#include ](https://stackoverflow.com/q/31816095/6865932) and [using namespace std;](https://stackoverflow.com/q/1452721/6865932) — anastaciu, Aug 05 '20 at 10:59

score 0 · Accepted Answer · edited Aug 05 '20 at 10:50

0

Try removing space before =.

for(int i=2; i*i<= num; i++) { ..

edited Aug 05 '20 at 10:50

mch

9,424
2
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answered Aug 05 '20 at 10:47

Ruchika Bobade

26
3

this worked but what the H. spaces aren't supposed to cause such problems – phatballz Aug 05 '20 at 10:51
1

This is because '<=' is an operator and you cannot add spaces between the symbols of the operator as '<' and '=' are two independent operators also exists. – Ruchika Bobade Aug 05 '20 at 10:57
Check this to learn more about c++ operators https://www.tutorialspoint.com/cplusplus/cpp_operators.htm – Ruchika Bobade Aug 05 '20 at 10:58
oh, I see. I never came across such a problem before. anyway, thanks. – phatballz Aug 05 '20 at 11:09

I'm getting error expected primary-expression before '=' for my for loop

1 Answers1