Expected expression error?

[stfnhill]

Can anyone tell me whats going wrong with this program? Trying to implement the trapezoidal rule:

template <class ContainerA, class ContainerB> (!EXPECTED EXPRESSION!)
double trapezoid_integrate(const ContainerA &x, const ContainerB &y) {
if (x.size() != y.size()) {
throw std::logic_error("x and y must be the same size");
}
double sum = 0.0;
for (int i = 1; i < x.size(); i++) {
sum += (x[i] - x[i-1]) * (y[i] + y[i-1]);
}
return sum * 0.5;

[Peter87]

Do you get the error on the line that you have written (!EXPECTED EXPRESSION!) or is that part of the code?

[stfnhill]

Yes

[Peter87]

Can you give the exact error message? My guess is that you have some problems in the lines above (like a missing ;) or that the error has something to do with the template arguments you use.

[stfnhill]

All it says on the side is "Parse Issue
Expected Expression"

[Peter87]

Can you post a complete example that can be compiled and gives this error?

[stfnhill]

{
}

template <class ContainerA, class ContainerB>
double trapezoid_integrate(const ContainerA &x, const ContainerB &y) {
if (x.size() != y.size()) {
throw std::logic_error("x and y must be the same size");
}
double sum = 0.0;
for (int i = 1; i < x.size(); i++) {
sum += (x[i] - x[i-1]) * (y[i] + y[i-1]);
}
return sum * 0.5;
}

[Peter87]

Remove the

{
}

[stfnhill]

Alright I did that, but i'm still getting the same error message

[zb0S216C]

I can think of a few reasons as to why you're receiving your error message:

1) You're missing either a closing brace/parenthesis/bracket/angle-bracket, or a semi-colon before the troublesome line.

2) You're declaring the template parameters "ContainerA", and "ContainerB", which are currenly in use somewhere else in your code.

_Wazzak