Question

Doesn’t do anything, it doesn’t even let me input when I call gets(), even my IDE is claiming “statement has no effect”.

#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

int main()
{
char userluv[800], fuusd[800], orig[800], key [51], priv [21];
int tempfussd[800], kint, pint, tint[5], c, lame;

//get the basic info
cout << "key? ";
cin >> key;
cout << "Second key? ";
cin >> priv;
cout << "Your lovely text?:\n";
gets(userluv);

for(c=0; c<=key[c]; c++){
    kint += key[c];
}
for(c=0; c<=priv[c]; c++){
    pint += priv[c];
}

//do stuff to your key
tint[0] = strlen(key) + strlen(priv);
tint[1] = tint[0] * tint[0];

//string to int then do stuff
    for(c=0; c<=userluv[c]; c++){
    tempfussd[c] = userluv[c];
    tempfussd[c] + kint;
    tempfussd[c] * pint;
    tempfussd[c] * tint[1];
}

    cout << "\n" << tempfussd[c] << "\n";

return 0;
}

Answer 1

These three lines are statements without effect:

tempfussd[c] + kint;
tempfussd[c] * pint;
tempfussd[c] * tint[1];

You may have omitted the = after the + and *?

The statements identified above occur in the loop:

for(c=0; c<=userluv[c]; c++){
    tempfussd[c] = userluv[c];
    tempfussd[c] + kint;
    tempfussd[c] * pint;
    tempfussd[c] * tint[1];
}

If (as hinted by a comment) the += and *= is correct, you could simplify things by writing:

for (c = 0; c <= userluv[c]; c++)
    tempfussd[c] = (userluv[c] + kint) * pint * tint[1];