今天弄了twitter这个鸟东东，并注册了跟gmail同名的用户名

Why define your own functions?

Readability

Maintainability

Code reuse

#include <iostream>
using namespace std;
int raiseToPower(int base, int exponent) {
int result = 1;
for (int i = 0; i < exponent; i = i + 1) {
result = result * base;
}
return result;
}
int main() {
int threeExpFour = raiseToPower(3, 4);
cout << "3^4 is " << threeExpFour << endl;
return 0;
}

 

 

Function delaration should be be set before function invocation.

 

Returning a value

 

Up to one value may be returned

Must be the same type as the return type

No need to be at the end

Returns the value as soon as a return statement is executed

Fucntion overloading

void printOnNewLine(int x)
{
cout << "1 Integer: " << x << endl;
}
void printOnNewLine(int x, int y)
{
cout << "2 Integers: " << x << " and " << y << endl;
}

 
Function prototypes are generally put into separate header files.

Recursion

Functions can call themselves

base case

recursive step

Pass by value(a) vs pass by reference(&a)