How do I fix this Expected Expression Error?

Question

I am trying to write a code for a project, and in my if else statements I want to put that the SWI is greater than or equal to 305 and less than or equal to 395. How would I place those limitations in the code? I tried using <= and >= , but I do not think the placement is correct, and I am confused on how to fix it.

#include <iostream>
#include <cmath>
using namespace std;

int main()
{

    double T,SWI,W;

    cout << "HELLO USER, PLEASE ENTER THE TEMPERATURE AND WIND SPPED TO PREDICT WEATHER FORECAST";
    cin >> T, W;

    SWI = 150*log10(T-49)+0.41*W+125*W/T;

    if (SWI < 305);{

        cout << "There is a low risk of severe thunderstorms.\n";
        cout << "However, still remain indoors and keep dry until the storm passes\n";

    }else if (SWI >= 305,SWI <= 395); {

        cout<< "Severe thunderstorms possible.\n";
        cout << "Please remain indoors and expect turbulant winds.\n";

    }else if(SWI > 395);{

        cout << "Severe thunderstorms imminent.\n";
        cout << "Stay off the roads and avoid any tall trees, possibility of tornadoes suspected.\n";
    }


    return 0;
} // end program

Answer 1

You have some syntactics errors. you should have something like:

if (SWI< 305){ //remove ; in every if and else

cout<< "There is a low risk of severe thunderstorms.\n"; 
cout << "However, still remain indoors and keep dry until the storm passes\n";

}else if (SWI<=395) { // if the execution falls in here is because SWI>=305

cout<< "Severe thunderstorms possible.\n";
cout << "Please remain indoors and expect turbulant winds.\n";

}else if(SWI > 395){

cout<< "Severe thunderstorms imminent.\n";
cout << "Stay off the roads and avoid any tall trees, possibility of tornadoes suspected.\n"; }

return 0; } 

Answer 2

There are too many syntactic errors. Corrected version below.

also you might need to consider a check on T . It must be >49 else the log function gets a -ve input.

#include <iostream>
#include <cmath>


int main()
{
    using namespace std;

    double T,SWI,W;

    cout << "HELLO USER, PLEASE ENTER THE TEMPERATURE AND WIND SPEED TO PREDICT WEATHER FORECAST";
    cin >> T;
    cin >> W;

    SWI = (150*log10(T-49))+(0.41*W)+(125*W/T);

    if (SWI < 305){

        cout << "There is a low risk of severe thunderstorms.\n";
        cout << "However, still remain indoors and keep dry until the storm passes\n";

    }else if (SWI <= 395) {

        cout<< "Severe thunderstorms possible.\n";
        cout << "Please remain indoors and expect turbulent winds.\n";

    }else {

        cout << "Severe thunderstorms imminent.\n";
        cout << "Stay off the roads and avoid any tall trees, possibility of tornadoes suspected.\n";
    }


    return 0;
} // end program