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Sample Technical Questions

C Sample Question

106. 	main()
     {
     	unsigned int i=65000;
     	while(i++!=0);
     	printf("%d",i);
     }

     Answer:

     1

     Explanation:

     Note the semicolon after the while statement. When the value of i becomes 0 it comes out of while loop. Due to post-increment on i the value of i while printing is 1.

107. main()
     {
     	int i=0;
     	while(+(+i--)!=0)
     		i-=i++;
     	printf("%d",i);
     }

     Answer:

     -1

     Explanation:

     Unary + is the only dummy operator in C. So it has no effect on the expression and now the while loop is, while(i--!=0) which is false and so breaks out of while loop. The value –1 is printed due to the post-decrement operator.

108. main()
     {
     	float f=5,g=10;
     	enum{i=10,j=20,k=50};
     	printf("%d\n",++k);
     	printf("%f\n",f<<2);
     	printf("%lf\n",f%g);
     	printf("%lf\n",fmod(f,g)); 
     }

     Answer:

     Line no 5: Error: Lvalue required
     Line no 6: Cannot apply leftshift to float
     Line no 7: Cannot apply mod to float

     Explanation:

     Enumeration constants cannot be modified, so you cannot apply ++.
     Bit-wise operators and % operators cannot be applied on float values.
     fmod() is to find the modulus values for floats as % operator is for ints.

109. main()
     {
     	int i=10;
     	void pascal f(int,int,int);
     f(i++,i++,i++);
     	printf(" %d",i);
     }
     void pascal f(integer :i,integer:j,integer :k)
     { 
     write(i,j,k); 
     }

     Answer:

     Compiler error: unknown type integer Compiler error: undeclared function write

     Explanation:

     Pascal keyword doesn’t mean that pascal code can be used. It means that the function follows Pascal argument passing mechanism in calling the functions.

110. void pascal f(int i,int j,int k)
     { 
     printf(“%d %d %d”,i, j, k); 
     }
     void cdecl f(int i,int j,int k)
     { 
     printf(“%d %d %d”,i, j, k); 
     }
     main()
     {
     	int i=10;
     f(i++,i++,i++);
     	printf(" %d\n",i);
     i=10;
     f(i++,i++,i++);
     printf(" %d",i);
     }

     Answer:

     10 11 12 13
     12 11 10 13

     Explanation:

     Pascal argument passing mechanism forces the arguments to be called from left to right. cdecl is the normal C argument passing mechanism where the arguments are passed from right to left.

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