Assignment 7

assignment7.txt

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+Yael Kelmer. 
+
+1. ++*p increments the value of the datatype located at pointer p and then points at that location. *p++ points at the location in memory of p and then increments the value there.  
+
+2. The left to right order is guaranteed for operator precedence. 
+
+
+3. One advantage of pointers is that you can move along a string and point to different parts of it. 
+
+4.1 datatype: char array
+4.2 this is invalid
+4.3 datatype: int. value: 0
+4.4 datatype: int. value: 10
+4.5 datatype: int. value: 10
+4.6 datatype: int. value: 12
+4.7 datatype: address. a[0]
+4.8 datatype: character
+4.9 datatype: address.
+4.10 datatype: int. value: 5

reverse.c

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+/* Yael Kelmer.
+ This code takes a user inputted string and uses a function that I created in order to print the string backwards. */
+
+#include <stdio.h>
+#include <string.h>
+
+void reversal (char userString[]) {
+	char *userStringStart = userString;
+	char *userStringEnd = userStringStart + strlen (userString) - 1;
+	int i;
+	for (i = 0; *userStringStart != *userStringEnd; i++) {
+		printf ("%c", *userStringEnd);
+		userStringEnd--;
+	}
+	printf ("%c\n", *userStringEnd);
+}
+
+
+
+int main () 
+{
+	printf ("Please type a string of letters\n");
+	char userString [100];
+	fgets (userString, sizeof(userString), stdin);
+	userString [strlen (userString) - 1] = '\0';
+	reversal(userString);
+}

stringFuncPointers.c

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+/* Yael Kelmer.
+   write a program that implements two functions: strcat() and strcmp(). use pointers. write the main function to execute both of these functions on 2 strings. */
+
+#include <stdio.h>
+#include <string.h>
+
+
+void stringCat (char string1[], char string2[]) {
+	int lengthString3 = strlen (string1) + strlen (string2);
+	char string3 [lengthString3];
+	char *string3Ptr = string3;
+	char *string1Ptr = string1;
+	char *string2Ptr = string2;
+	int i;
+	for (i = 0; i < strlen (string1); i++) {
+		*string3Ptr = *string1Ptr;
+		string3Ptr++;
+		string1Ptr++;
+	}
+	for (i = 0; i < strlen (string2); i++) {
+		*string3Ptr = *string2Ptr;
+		string3Ptr++;
+		string2Ptr++;
+	}
+	*string3Ptr = '\0';
+	printf("%s\n", string3);
+}
+
+int stringCmp (char string1[], char string2[]) {
+	int shorterLength;
+	if (strlen (string1) < strlen (string2)) {
+		shorterLength = strlen (string1);
+	}
+	else {
+		shorterLength = strlen (string2);
+	}
+	char *string1Ptr = string1;
+	char *string2Ptr = string2;
+	int i;
+	for (i = 0; i < shorterLength; i++) {
+		if (*string1Ptr == *string2Ptr) {
+			string1Ptr++;
+			string2Ptr++;
+		}
+		else if (*string1Ptr < *string2Ptr) {
+			return 1;
+		}
+		else if (*string1Ptr > *string2Ptr) {
+			return -1;
+		}	
+	}
+	if (strlen (string1) == strlen (string2)) {
+		return 0;
+	}
+	else if (strlen (string1) < strlen (string2)) {
+		return 1;
+	}
+	else if (strlen (string1) > strlen (string2)) {
+		return -1;
+	}
+} 
+
+
+
+int main() {
+
+	char string1 [] = "hello";
+	char string2 [] = "world";
+	printf ("This is the concatenation of string1 and string2: ");
+	stringCat(string1, string2);
+	int comparison = stringCmp(string1, string2);
+	printf ("This is the comparison of string1 and string2: %d\n", comparison);
+}