SSD06 Practical Quiz 2 个人解答

1.

Are there any memory errors in the following program? If so, identify all of the errors and provide a corrected code fragment to alleviate the problem. Assume that the user enters in correct input, and that the sizes entered are at least one. Write your solution in a text or Word file and submit it below. void main() { char *str, *input; int *ilist; int i, size1, size2; printf("Number of letters in word: "); scanf("%d", &size1); /* user inputs an integer */ printf("Number of integers: "); scanf("%d", &size2); /* user inputs an integer */ str = (char *) malloc(size1); ilist = (int *) malloc(size2); printf("Word: "); scanf("%s", str); /* user inputs a string */ for(i = 0; i < size2; i++) { printf("Number %d of %d: ", i + 1, size2); scanf("%d", ilist + i); /* user inputs an integer */ } }

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2.

Are there any memory errors in the following program? If so, identify all of the errors and provide a corrected code fragment to alleviate the problem. Write your solution in a text or Word file and submit it below. /* return 1 if str is "1", 0 otherwise */ int checkIf1(char *str) { char *newstr = malloc(strlen(str) + 1); strcat(newstr, str); /* set newstr to str */ if (strcmp(newstr, "1") == 0) { /* newstr is "1" */ return 1; } free(newstr); return 0; } void main() { char *strArr[4] = {"1", "2", "3", "4"}; int i; for(i = 0; i < 4; i++) { printf("%d\n", checkIf1(strArr[i])); } }

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3.

Are there any memory errors in the following program? If so, identify all of the errors and provide a corrected code fragment to alleviate the problem. Write your solution in a text or Word file and submit it below. struct data { char *str1, *str2; }; /* returns two strings concatenated if they are not the same, NULL otherwise */ char *mergeSingleIfDifferent(char *s1, char *s2) { char *str = (char *) malloc(strlen(s1) + strlen(s2) + 1); if (strcmp(s1, s2) == 0) { /* strings are equal */ str = NULL; } else { strcpy(str, s1); strcat(str, s2); } return str; } /* copies merged strings (or NULL) into array of strings passed in (results) */ void mergeArrayIfDifferent(char *results[], char *strA1[], char *strA2[], int size) { int i; for(i = 0; i < size; i++) { results[i] = mergeSingleIfDifferent(strA1[i], strA2[i]); } } void printAndFree(int c, char *str) { if (str != NULL) { printf("%d: %s\n", c, str); free(str); } } void main() { char *strArr1[8] = {"1", "2", "3", "4", "5", "6", "7", "8"}; char *strArr2[8] = {"a", "2", "c", "4", "e", "6", "g", "8"}; char *results[8]; int i; mergeArrayIfDifferent(results, strArr1, strArr2, 8); for(i = 0; i < 8; i++) { printAndFree(i, results); } }