swapping two numbers

int a = 8;
int b = 9;

swapping needs
int temp = a;
a= b;
b= temp;

Problem: how to avoid using an extra variable temp?

a = a+b; // a==8+9=17 b== 9
b = a-b; // a==17 b=17-9=8
a = a-b; // a==17-8=9 b==8

a = a-b; // a==8-9=-1 b== 9
b = b+a; // a==-1 b=9+(-1)=8
a = b-a; // a==8-(-1)=9 b==8

OR

a= a*b; // a==8X9=72 b==9
b= a/b; // a==72 b=72/9=8
a= a/b; // a==72/8=9 b==8

OR

a=a/b;..
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OR

a= a^ b;...
b=log......
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OR
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