If statement for multiple values of same variable

user_15387341 0
Viewed 2293

I want to apply if statement to check a condition with multiple values, which I know should be something like this:

if (value == 1 || value == 2 || value == 3 || value == 4)
    //Do something;

But this does not look good, isn't there any way to check like:

if(value == 1 || 2 || 3 || 4)

Note: I am not trying something in range like:

if (1 <= value && value <= 4)
conditional-statements if-statement c++
5 Answers

No you can not write it as : if(value==1 || 2 || 3 || 4)

You can use conditional statement for different conditions.

user_164270750

A possible simple alternative would be:

switch (value) { case 1: case 2: case 3: case 4: std::cout << "true"; }

Live sample

Wether it looks better or not is a matter of taste.

Another alternative would be:

switch (value) { case 1 ... 4: std::cout << "true"; }

Live sample

But this is not standard C++, I believe it's a GNU extension.

user_68659320

In case the range of possible values is smaller than the number of bits you can do something like this:

int value = 2;
auto values = {1,2,3,4};
int test = 0;
for(auto i : values)
    test |= (1 << i);

if((1 << value) & test)
    std::cout << "true" << std::endl;

If you have direct control over the possible values you can also directly set them as bitflags and skip the bitshift part.

Otherwise there is also the option of inverting the condition in case there are fewer possible values that should evaluate to false.

Also you could just loop over an array of valid values and see if any of them matches.

user_13665910

No you cannot write the way you have described. You still have option of switch case and ternary operators. If you want to make it fancy you still have option like

vector<int> v = {1,2,3,4,5}; // desirable values
auto it = find(v.begin(), v.end(), value);
if(it != v.end()){
    cout<<"value is equal to something!\n";
    // if you want to check which value does it match to
    cout<<"Matching value is at index "<<it-v.begin()<<"\n";
}else {
    cout<<"Value is not equal to any number!\n";
}

For this you will need to include vector library by using #include <vector>

user_134466330

Well, I had the same issue and this is the solution I came up.

I created an array, with the values I want to check, and then I use the native array includes() method to check if the variable value exists on the array. Like this:

[1, 2, 3, 4].includes(value);

If the variable value exists on the array the includes() method will return a boolean with the value true. Otherwise it will return a boolean with the value false.

user_118608000
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