1 #include 
     
        2 int main()  3 {
    4     int a = 10,b=20;  5 //  solution 1: a = a+b; b = a-b; a = a-b;  6     printf("*********************************************\n");  7     printf("Change two number without another number!!!!\n");  8     printf("*********************************************\n");  9     printf("Solution 1:\n"); 10     printf("a:%d b:%d\n",a,b); 11     a = a + b; 12     b = a - b; 13     a = a - b; 14     printf("a:%d b:%d\n",a,b);    15     printf("*********************************************\n"); 16     printf("Solution 2:\n"); 17 //  solution 2: 18     a = 10; 19     b = 20; 20     printf("a:%d b:%d\n",a,b); 21     a = a*b; 22     b = a/b; 23     a = a/b; 24     printf("a:%d b:%d\n",a,b); 25     26     printf("*********************************************\n"); 27     printf("Solution 3:\n"); 28 //  solution 3:a^=b^=a^=b; 29     a = 10; 30     b = 20; 31     printf("a:%d b:%d\n",a,b); 32     a = a^b;//put the information into a 33     b = a^b;//make b equal to the orginal a 34     a = a^b;//make a equal to the orginal b 35     printf("c:%d d:%d\n",a,b); 36 37     return 0; 38 }