Control may reach end of non-void function error if-statement - ios

Question

I'm getting the error Control may reach end of non-void function on this code:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if (changeData.selectedSegmentIndex == 0) {
return self.tweets.count;
} else if (changeData.selectedSegmentIndex == 1) {
return self.tweets1.count;
} else if (changeData.selectedSegmentIndex == 2) {
return self.tweets2.count;
}
}
Why?

Answer 1

Because when your all if condition fails, you are not returning anything from the function.
Also multiple return statement in a function is not a good practice.
Do it like:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
int count = 0;
if (changeData.selectedSegmentIndex == 0)
{
count = self.tweets.count;
}
elset if (changeData.selectedSegmentIndex == 1)
{
count = self.tweets1.count;
}
else if (changeData.selectedSegmentIndex == 2)
{
count = self.tweets2.count;
}
return count;
}

Answer 2

Midhun MP has your answer and better code style. I would strongly advice replacing all those nested else-ifs with a switch-statement as, well you don't really want else-ifs if you can avoid them...
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
NSInteger count = 0;
switch (changeData.selectedSegmentIndex)
{
case 0:
count = self.tweets.count;
break;
case 1:
count = self.tweets1.count;
break;
case 2:
count = self.tweets2.count;
break;
default:
break;
}
return count;
}

Answer 3

If you think its ok disable it:

Answer 4

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSInteger count = 0;
if (changeData.selectedSegmentIndex == 0) {
count = self.tweets.count;
} else if (changeData.selectedSegmentIndex == 1) {
count = self.tweets1.count;
} else {
count = self.tweets2.count;
}
return count;
}
or
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSInteger count = 0;
if (changeData.selectedSegmentIndex == 0) {
count = self.tweets.count;
} else if (changeData.selectedSegmentIndex == 1) {
count = self.tweets1.count;
}
else if (changeData.selectedSegmentIndex == 2){
count = self.tweets2.count;
}
return count;
}

Answer 5

While I agree with most answers that suggest to avoid multiple returns in the general, on occasions multiple returns is nice and useful. For instance dispatching on an enum:
#include <iostream>
#include <string>
enum direction { north, east, south, west };
std::string to_string(direction d)
{
switch (d)
{
#define CASE(C) case C: return #C
CASE(north);
CASE(east);
CASE(south);
CASE(west);
#undef CASE
}
}
int main()
{
std::cout << to_string(west) << '\n';
}
If you compile with GCC, you get (C or C++, it's the same):
$ g++-4.9 -Wall foo.cc
foo.cc: In function 'std::string to_string(direction)':
foo.cc:17:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
Clang does not complain. Which is not so nice, actually, since it also compiles this without warnings:
int main()
{
std::cout << to_string(direction(666)) << '\n';
}
which results in:
$ clang++-3.5 -Wall foo.cc
$ ./a.out
zsh: illegal hardware instruction ./a.out
So one has to "fight" GCC's warning. One wrong approach would be to add say
default: abort();
to the switch. Sure, it cures the symptom, but now GCC will no longer complain if I add a new direction, say zenith, but forget to cover it in to_string. So really, never use a default case when switching on an enum.
Then you can leave an abort after the switch (which is clumsy to do without using inner returns).