school_archives/OSU Coursework/CS 161 - Intro to Programming I/Assignments/Assignment 2/perrenc_hw1.txt

Corwin Perren - 931759527
Assignment 2 - ECE151
Written Questions


Problem 1(10.2)
	a. 
	Original code:
		char str[5];
		scanf("%s", str); /* User types hello */

	Fixed code:
		char str[5];
		scanf("%s", &str); //user types hello
	Explanation:
		An ampersand is needed to store the value to memory, and the commenting 
		is inconsistent with the style guide.

	b. 
	Original:
		int a[3];
		printf("%d  %d  %d\n", a[1], a[2], a[3]);
	Fixed:
		int a[3] = {1, 3, 5};
		printf("%d  %d  %d\n", a[0], a[1], a[2]);
	Explanation:
		The original creates an empty array with no values in it, which makes it
		impossible to print its contents. The location in memory is dumped. Also,
		the locations printf is pulling from are one block off. The first value 
		has location [0,0], not [1,1]. 

	c. 
	Original:
		double f[3] = {1.1, 10.01, 100.001, 1000.001};
	Fixed:
		double f[4] = {1.1, 10.01, 100.001, 1000.001};
	Explanation:
		The array is not large enough.

	d. 
	Original:
		double d[2][10];
		d[1,9] = 2.345;
	Fixed:
		float d[2][10];
		d[1][9] = 2.345;
	Explanation:
		Used incorrect location mapping and the double was not big enough to 
		handle this decimal.



Problem 2(10.4)

Original:
	int N;
	int M=90;

	int funct4(int n) {
		int i;
		int m = n;
		int a[n][n];
		int b[n][m];
		int c[printf("%d\n", n)][n];
		int d[n][N];
		int e[n][M];
		int f[n] = {1, 2, 3, 4};
		static int g[n];
	
		for(i=0; i<n; i++) {
			a[i][i] = 3+b[i][i];

		}
		funct4(4);

	Fixed (option 1):

		int funct4(int n) {
			int N; // these two should be initialized within the function
			int M = 90; //spacing
			int i;
			int n = 50; //int n needed, with value
			int m = n;
			int a[n][n];
			int b[n][m];
			int c[n][n]; //removed print statement (unnecessary)
			int d[n][N];
			int e[n][M];
			int f[n] = {1, 2, 3, 4};
			static int g[n];

			for(i=0; i<n; i++) {
				a[i][i] = 3+b[i][i];

			}
       } //end bracket needed
		funct4(4); //sets n = 4

Fixed (option 2):

       int funct4(int n) {
		int n; //no capital letters allowed
		int m = 90 //no capital letters allowed
		int i;
		int m = n;
		int a[n][n];
		int b[n][m];
		int c[n][n]; //removed print statement (unnecessary)
		int d[n][n]; //no capital letters allowed
		int e[n][m]; //no capital letters allowed
		int f[ ][n] = {1, 2, 3, 4}; //needed first dimension brackets
		static int g [ ][n]; //needed first dimension brackets

		for(i=0; i<n; i++) {
			a[i][i] = 3+b[i][i];

		}
       } //end bracket needed
	funct4(4);

Prob 3(11.1)
	a. No errors, just prints an empty value.
	b. Fixed:
		float *realPtr;
		int *integer pointer;
		*integerPtr = (int) *realPtr //needed asterisks and typecasting.
	c. Fixed:
		int *x, y;
		x = &y; //need to specify that y is the target of the pointer x
	d. Fixed:
		int i; //needs a looping variable
		char s[] = 'this is a character array";
		for(i = 0; *(s+1) != '\0'; i++) { //needs loop assignment, parentheses, 
						  // and brackets
			printf("%c", *(s+i)); //matches original pointer
		} //needs end bracket
	e. Fixed:
		short *numPtr, result;
		void *genericPtr = numPtr;
		result = ((short) *genericPtr) + 7; //needs typecast change
	f. Fixed:
		float x = 19.34;
		float *xPtr = &x; //missing splat
		printf("%f\n", xPtr);
	g. Fixed:
		char *s;
		printf("%c\n", *s); //since s is a char, it should be %c, and it also 
				    //needs to be *s, since that's the real name
	h. Fixed:
		int funct1(int *p){
			int i = -1;
			int *pp;
			return i; //it doesn't return a pointer 
		}

		int main(int argc, char **argv){ //main needs arguments
			int i = 5;
			funct1(&i); //makes int *p point to the address of i, not the 
				    //value.
		}		



Problem 4(11.2)
	a. False. Pointers can always be dereferenced to be compared.
	b. True. 

Problem 5(11.3)
	a. long long int *11ptr;
	b. 11ptr = &value1;
	c. printf("%d\n", *11ptr);

Problem 6(11.4)
	a. int main(int argc, char **argv) {
		int count = 0;
		int a[10];
		int *p = (int *) malloc(10*sizeof(int));

		for(count = 0; count < 10; count++) {
			a[count] = 5;
		}
		free (int *p);
		return 0;
	}

	b. char *str = (char *) malloc(10 * sizeof("this string"));


Problem 7(11.8)
	This application tries to scan two strings and print only the first, but  because
	of the error on line "scanf("%s%s", string1, string2);", it puts both strings 
	into string1 and prints them consecutively.

Problem 8(11.9)
	This application scans a user string and outputs its length.

Problem 9(11.21)

       Original test value: 
		a[1][2] (8)
       in int a[3][5] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
	everything that isn't equal to 8 is false
Test Code Output: 
	8 - A
	8 - C
	8 - D
	8 - E
	4 - F
	-1071285860 - G
	8 - H
	6 - I
	8 - J
	-1071285780 - K
	8 - L
	8 - M
	5 - N
	7 - O
	-1071285800 - P
	9 - Q
B wouldn't even run as given.
True Values: A, C, D, E, H, J, L, M
False Values: F, G, I, K, N, O, P, Q


10. In logical operations, there is a concept known as short circuiting. What this means 
is that as soon as a logical expression's truth value can be determined, evaluation 
stops. For instance, with an OR statement, if the first portion is TRUE, the second would
not be evaluated in a short circuit evaluation system. Discuss how you might determine 
whether C uses short circuit evaluation. Consider implementing your idea to test it. Did 
it work? Include any lines of code necessary to test within the text file.

Yes, C uses short circuit evaluation. The follow function returned:
"Yup, it worked.
That worked too."



#include <stdio.h>

#define x 5
#define y 10

int main (int argc, char **argv) {

	if ((x == 5) | (x == 6)) {
		printf("Yup, it worked.\n");
	}

	if ((x == 6) | (y == 10)) {
		printf("That worked too.\n");
	}
 	return 0;

}