Function<\/p>\n
\nvoid TestPassByPointer(){
\nint num = 10;
\nIncr10(&num);
\nreturn;
\n}
\n\/\/ Pass by a copy of pointer
\n\/\/ so same memory address
\nint Incr10(int* num){
\n*num += 10;
\nreturn *num;
\n}<\/code><\/li>\n- Pass by reference
\n
\nvoid TestPassByRef(){
\nint num = 10;
\nint& rnum = num;
\nIncr_10(rnum);
\nreturn;
\n}
\n\/\/ Pass by reference
\n\/\/ Changes the original variable directly
\nint Incr_10(int& num){
\nnum += 10;
\nreturn num;
\n}<\/code><\/li>\n- Mandate that parameter not be changed\n
\n- int increase10(const int& num);<\/li>\n<\/ul>\n<\/li>\n
- Initialize parameters\n
\n- int myfxn(long arg1 = 10, long arg2 = 20);<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n
- Return values\n
\n- Return pointer\n
\n- Never return the address of a local variable from a function (memory is gone!)<\/li>\n
- Instead, return a pointer to free store and don’t forget to delete (memory leak!)
\n
\ndouble* treble(double data)
\n{
\n\/\/ Allocate memory in the heap
\ndouble* result = new double(0.0);
\n\/\/Check out of memory
\nif (!result){
\ncout << \"Out of memory...\" << endl;
\nexit(1);
\n}
\n*result = 3.0*data;
\nreturn result;
\n}
\nvoid TestReturnPointer()
\n{
\ndouble num = 10.0;
\ndouble* ptr = 0;
\nptr = treble(num);
\ncout << \"three times \" << num << \" is \" << *ptr << endl;
\ndelete ptr; \/\/ Don't forget to delete!
\nreturn;
\n}<\/code><\/li>\n<\/ul>\n<\/li>\n- Return reference<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
Pointer to function<\/p>\n
\n- Declare\n
\n- return_type (*pointer_name) (list_of_parameter_types);<\/li>\n
- double (*pfun) (char*, int);<\/li>\n<\/ul>\n<\/li>\n
- Example
\n
\nvoid TestFunctionPointer()
\n{
\n\/\/ Declar a function pointer
\nlong (*fptr)(long, long);
\n\/\/ Assign fxn pointer to product
\nfptr = product;
\ncout << fptr(3, 5) << endl;
\n\/\/ Assign fxn pointer to sum
\nfptr = sum;
\ncout << fptr(3, 5) << endl;
\n}
\nlong product(long a, long b)
\n{
\nreturn a*b;
\n}
\nlong sum(long a, long b)
\n{
\nreturn a+b;
\n}<\/code><\/li>\n- Function pointer can be passed as parameter\n
\n- double sumarray(double [] array, int len, double (*pfun)(double));<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
Function Template<\/p>\n
\n- Example
\n
\n\/\/ Define template
\ntemplate<\/class> T max(T x[], int len)
\n{
\nT max = x[0];
\nfor (int i = 0; i < len; i++)
\n{
\nif (max < x[i])
\nmax = x[i];
\n}
\nreturn max;
\n}
\nvoid TestFunctionTemplate()
\n{
\nint small[] = {1, 25, 35, 15};
\nint lensmall = sizeof small\/sizeof small[0];double medium[] = {25, 250, 2500, 5, 450};
\nint lenmedium = sizeof medium\/sizeof medium[0];cout << \"Max of small: \" << max(small, lensmall) << endl;
\ncout << \"Max of medium: \" << max(medium, lenmedium) << endl;
\n}<\/code><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"Function Need to include function prototype before function can be used void DoMagic(Magic name); Passing parameters C++ is pass by value Use pointer to pass by pointer (dah) void TestPassByPointer(){ int num = 10; Incr10(&num); return; } \/\/ Pass by … Continue reading