Oscar So

assignment7.txt

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+Oscar So
+1. First one means, ++(*p) adds one before implementing pointer. Second one is (*P++), but precedence of ++ is treated before P. Last one is similar to the second one, but it is treated as (*++P) where the compiler looks for associativity.
+2. I think both do not guarentee operator precedence, this is because in postfix, &&, ||, mathematical functions, comparison, the computer code reads it from left to right. However, for conditions, assignment of variables, and prefixes, the code goes from right to left. 
+3. Advantages of pointers are when handling arrays, and data tables. They allow references to functions, and can return multiple variables and values.
+4. I am a bit clueless on number 4 and would like some explanation. Thanks.

reverse.c

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+#include<stdio.h>
+#include<string.h>
+void reverse(char *input){
+	int length, i;
+	char *start, *stop, temp;
+	length = strlen(input);
+	start=input;
+	stop=input;
+	for(i=0;i<length-1;i++){
+		stop++;
+	}
+	for(i=0;i<length/2;i++){
+		temp=*stop;
+		*stop=*start;
+		*start=temp;
+		start++;
+		stop--;
+	}
+}
+int main() {
+	char input[200];
+	printf("Please input string: \n");
+	fgets(input,sizeof(input),stdin);
+	strtok(input,"\n");
+	reverse(input);
+	printf("The reverse is: \n");
+	printf("%s \n", input); 
+}

string1.c

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+#include<stdio.h>
+#include<string.h>
+char *cat (char *p1, char *p2){
+	int i=0, p3= strlen(p1);
+	while(p2[i]!='\0'){
+			p1[p3]=p2[i];
+			p3++;
+			i++;
+	}
+	p1[p3]='\0';
+	return p1;
+}
+
+int main(){
+	char p1[50], p2[50];
+	printf("Enter first string: ");
+	fgets(p1,sizeof(p1),stdin);
+	printf("Enter second string: ");
+	fgets(p2,sizeof(p2),stdin);
+	strtok(p1,"\n");
+	strtok(p2,"\n");
+	cat(p1,p2);
+	printf("New string: %s \n",p1);
+}

string2.c

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+#include<stdio.h>
+#include<string.h>
+int compare(char *p1, char *p2){
+	while (*p1==*p2){
+		if (*p1 == '\0' || *p2 == '\0'){
+			printf("Dissimilar User Input \n Error \n");
+			break;
+		}
+		p1++;
+		p2++;
+	}
+	if (*p1=='\0' && *p2 == '\0'){
+		return 0;
+	}else if (*p1=='\0'){
+		return 1;
+	}else if (*p2 == '\0'){
+		return -1;
+	}
+}
+int main () {
+	int result;
+	char p1 [100], p2 [100], final;
+	printf("Input first string: ");
+	fgets(p1, sizeof(p1),stdin);
+	printf("Input second string: ");
+	fgets(p2, sizeof(p2),stdin);
+	strtok(p2, "\n");
+	strtok(p1, "\n");
+	result = compare (p1,p2);
+	if (result == 0){
+		printf("Both strings are the same. \n");
+	}else if(result == -1) {
+		printf("Input 1 is longer than Input 2. \n");
+	}else if (result ==1) {
+		printf("Input 1 is shorter than Input 2. \n");
+	}
+}