testing == in a loop

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Original post by Matty_alan why can't you test if x is equal to y in say a for loop

for (int i = 0; i == 10; ++i){    std::cout << i << std::endl;}

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Original post by Matty_alan Iv'e come accross this problem a few times now, why can't you test if x is equal to y in say a for loop but you can test < and >, It seems strange that it'll let you test < and > but restirct you from using ==

int escapedMentalPatients = 0;int allowableEscapes = 0;while( escapedMentalPatients == allowableEscapes ){  if( rand()%2 )    escapedMentalPatients++;}SoundAlarm();

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Original post by DevFred Quote: Original post by Matty_alan why can't you test if x is equal to y in say a for loop Sure you can, but it's probably not what you want. for (int i = 0; i == 10; ++i){ std::cout << i << std::endl;} Here, the loop body will be executed 0 times, because 0 == 10 is false.

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Original post by Hodgman Quote: Original post by Matty_alan Iv'e come accross this problem a few times now, why can't you test if x is equal to y in say a for loop but you can test < and >, It seems strange that it'll let you test < and > but restirct you from using == Can you give an example of when you're not allowed to use ==?*** Source Snippet Removed ***

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Original post by Matty_alan Quote: Original post by DevFred Quote: Original post by Matty_alan why can't you test if x is equal to y in say a for loop Sure you can, but it's probably not what you want. for (int i = 0; i == 10; ++i){ std::cout << i << std::endl;} Here, the loop body will be executed 0 times, because 0 == 10 is false. I cut and pasted that loop directly into a program and it didn't give any output here is an exact copy paste of it... #include int main() { for (int i = 0; i == 10; i++) { std::cout << i << std::endl; } system("pause"); } if i change this to for (int i = 0; i <= 10; i++) it works perfect

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Original post by Matty_alan I cut and pasted that loop directly into a program and it didn't give any output

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Original post by DevFred Here, the loop body will be executed 0 times, because 0 == 10 is false.

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Original post by Matty_alan Quote: Original post by DevFred Quote: Original post by Matty_alan why can't you test if x is equal to y in say a for loop Sure you can, but it's probably not what you want. for (int i = 0; i == 10; ++i){ std::cout << i << std::endl;} Here, the loop body will be executed 0 times, because 0 == 10 is false. I cut and pasted that loop directly into a program and it didn't give any output here is an exact copy paste of it... #include int main() { for (int i = 0; i == 10; i++) { std::cout << i << std::endl; } system("pause"); } if i change this to for (int i = 0; i <= 10; i++) it works perfect

int i = 0;while (i == 0){    // do something    i = 2;}

for (int i=1; ((i%5)==0) && ((i%7)==0); ++i){    cout << i;}

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Original post by iMalc Here's a contrived way to code a loop from 1 to 34 that uses two =='s: for (int i=1; ((i%5)==0) && ((i%7)==0); ++i){ cout << i;} Point being, there's nothing stopping you from using == in a loop except logic.

for (int i=1; ((i%5)!=0) && ((i%7)!=0); ++i){    cout << i;}

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Original post by iMalc Here's a contrived way to code a loop from 1 to 34 that uses two =='s: for (int i=1; ((i%5)==0) && ((i%7)==0); ++i){ cout << i;} Point being, there's nothing stopping you from using == in a loop except logic.

for (int i=0; i==0 || i==1 || i==2 || i==3 || i==4 || i==5 || i==6 || i==7; ++i){    cout << i;}

for (int i = 0; (i < 10) == true; ++i){    std::cout << i << std::endl;}

template<typename T>class EverythingElse<T>{public:    EverythingElse(T x) : x(x) { }    template<typename U>    bool operator==(U const& other) { return x != other; }        template<typename U>    bool operator!=(U const& other) { return x == other; }    private:    T x;};template<typename T>EverythingElse<T> AnythingBut(T x) { return EverythingElse<T>(x); }for(int i=0; i == AnythingBut(10); i++){    std::cout << i << std::endl;}