CS220 Week 4 Homework Due Feb. 26, 2016

Name:

1. Given the following C code:
	int x = 1000000001;
	float fx=x;
	if (x==fx) printf("x and fx are the same");
	else printf("x and fx are different");
	
   ... what will get printed?  Why?
   
2. Given the following C code:
	int func(char a[],char b[]) {
		while((*a)) if (*a++)!=(*b++)) return 0;
		if ((*b)) return 0;
		return 1;
	}
	
   a) What will func("string 1","string 1") return?
   b) What will func("string 1","string") return?
   c) What does func do?
   
 3. Are the following statements true or false...
 	
 	a) ___ If the only command I type in a gdb session is "run", then my program will run to completion.
 	
 	b) ___ In gdb, if I type "n", and hit enter twice, I will execute exactly two C statements
 	
 	c) ___ In gdb, if I type "b 21 if (i>20)", then gdb will stop the next time I execute line 21
 	
 	d) ___ In gdb, if I type "p myfn(x*3)", where x is a variable and myfn is a function in my
 		code, then gdb will print out the return value of myfn.
 		
 	e) ___ It is possible in gdb to set a breakpoint at line 54 of my code, and print out the value
 	       of a variable every time that breakpoint is reached.
 	       
4. Given the following C code (where %p in printf means print the hexadecimal value of a pointer):

	int vec[4]={6,7,8,9};
	int * vecptr=vec;
	printf("Vector is at %p\n",vecptr);
	printf("vec[2] is at %p\n",vecptr+2);
	printf("vec[2] is not at %p\n", (char *)vecptr+2);
	
   If the first printf statement results in "Vector is at 0x5fcb00", 
   
   	a) What will the second printf statement print?
   	
   	b) What will the third printf statement print?
   
5. Given the following C code:

	int matrix[2][3];
	int *mptr=&matrix[0][0];
	int row; int col;
	for(row=0; row<2; row++) {
		for(col=0; col<3; col++) {
			matrix[row][col]=(row*10) + col;
		}
	}
	printf("The fifth element of matrix is %d\n",*(mptr+5));
	
   What will the printf statement print?