else if不执行，想知道那里错了

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    int T,A,B;
    char C[10000];
    while (cin >> T )
    {
        for (int i = 1; i <= T; i++)
        {
            cin >> C[i] >> A >> B;
        }
        for (int i = 1; i <= T; i++)
        {
            double c=0;
            if (C[i] = '+')
            {
                c = A + B;

            }
            else if (C[i] = '-')
            {
                c = A - B;
            }
            else if (C[i] = '*')
            {
                c = A * B;

            }
            else if (C[i] = '/')
            {
                c = A / B;
            }
            cout << fixed << setprecision(2) <<c <<endl;
        }

    }
}

想要输入输出这样

但现实是这样

=是赋值，应该用==

==不是=