Operator¶
you can watch parallel the video for C/C++ (german): https://www.youtube.com/watch?v=5iL-onZ6M5U&list=PLEWVM-KBUSpmWSfyoFdD_hLWAY_9tTgi5&index=13
Be aware of differences in operator precedence between c/c++ javascript on the one side and python on the other side especially with regard to the bitwise operators and equality and comparison operators. https://stackoverflow.com/questions/8649738/cs-heritage-bitwise-operators-vs-equality-operators-precedence https://www.sololearn.com/en/Discuss/1823439/difference-of-operator-precedence-between-c-and-python
we will see that in detail in the next chapter about bitwise operators
import ROOT
C++/C and Javascript¶
https://discuss.codechef.com/t/operator-precedence-table/14545
C++¶
C¶
javascript¶
%%cpp
cout <<3+4*5<<endl; //Precedence
23
%%cpp
int c=1;
++c;
cout <<c<<endl;
2
%%cpp
int c=1;
cout <<++c<<endl;
2
%%cpp
int c=1;
cout <<c++<<endl;
cout <<c<<endl;
1 2
%%cpp
int c=1;
cout <<--c<<endl;
cout <<c--<<endl;
cout <<c<<endl;
0 0 -1
%%cpp
int c=1;
c-=1;
cout <<c<<endl;
c+=1;
cout <<c<<endl;
c*=2;
cout <<c<<endl;
c/=2;
cout <<c<<endl;
c=11;
c%=10; //Modulo operation
cout <<c<<endl;
0 1 2 1 1
There is no power operator in c/c++. You need to use a function from cmath. Attention ^ is the binary xor operator.
%%cpp
#include <cmath>
cout <<pow(2,3);
8
Javascript has the power operator ** wich is equivalent to Math.pow(a,b) with the highest precedence right between 14 and 15 and is not mentioned in the above table.
%%js //the next line is only necessary in jupyter notebooks
element.setAttribute('style', 'white-space: pre;');console.log=function(text){element.textContent+=text+"\n"}
console.log(2**5)
console.log(2**(3**4))
console.log(2**3**4)
Python¶
Be aware of a sutle difference in the operator precedence of the Comparison operators as compared to c/c++ where the equality and unequality operator have less precedence.
https://learningmonkey.in/courses/python/lessons/operator-precedence-and-associativity-in-python/
print(2**4)
16
Remark¶
Python behaves different with regard to the precedence comparison operator has the same precedence to equality or inequality operator:
print(1<2==1)
#should according to table be evaluated as
print((1<2)==1) #oops but that is not the case
#the comparison operators are actually a special case as the table above is actually wrong here
#because python allows for
print(1<2<3)
#and is to be read as
print(1<2 and 2<3)
#lets check
print(1<2 and 2==1) #yep
False True True True False
%%cpp
cout << (1<2==1) <<endl;
//this is evaluated as
cout << ( (1<2)==1) <<endl;
1 1
%%js //the next line is only necessary in jupyter notebooks
element.setAttribute('style', 'white-space: pre;');console.log=function(text){element.textContent+=text+"\n"}
console.log((1<2==1))
2**3**4==2**(3**4) # the ** operator is Right to left associative
True
