C + + function templates

If you compare two different types of values, you might write out the following code:

int Compare (conststringconststring &v2) {    if (V1 < v2) {        return -1;    }     if (V2 < v1) {        return1;    }     return 0 ;}

int Compare (constdoubleconstdouble &v2) {    if (V1 < v2) {        return -1;    }     if (V1 > v2) {        return1;    }     return 0 ;}

These two functions are not the same as the numerical comparison class, the function body is the same, and rewrite the trouble.

We need the template now.

Template <typename t>int Compare (constconst T &v2) {    if ( V1 < v2) {        return -1;    }     if (V1 > v2) {        return1;    }     return 0 ;}

It can be done with a function body, which is called a generic function template.

1. Definition

The template definition starts with a keyword, followed by the templates parameter list, which is a comma-delimited list of one or more stencil parameters, wrapped with less than < and greater than sign >.

2. Instantiation

When the template is defined, the call is instantiated.

cout << Compare (12) << Endl; // Compare (const int &V1, const int &v2)

Because the compiler encounters a template definition, it does not generate code. The compiler generates code only when you instantiate a specific version of the template. This feature affects how we organize the code and when the error is detected.

C + + function templates