From 6883e1b192bda14d403a4731f472b92ef0438c7d Mon Sep 17 00:00:00 2001
From: Bao Mai <bgm47@drexel.edu>
Date: Sun, 19 Jan 2025 22:30:43 -0500
Subject: [PATCH] update assignment 1
---
1-C-Refresher/stringfun.c | 252 ++++++++++++++++++++++++++++++++++++++
1 file changed, 252 insertions(+)
create mode 100644 1-C-Refresher/stringfun.c
diff --git a/1-C-Refresher/stringfun.c b/1-C-Refresher/stringfun.c
new file mode 100644
index 0000000..1c74d56
--- /dev/null
+++ b/1-C-Refresher/stringfun.c
@@ -0,0 +1,252 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+#define BUFFER_SZ 50
+
+//prototypes
+void usage(char *);
+void print_buff(char *, int);
+int setup_buff(char *, char *, int);
+int count_words(char *, int, int);
+void reverse(char *, int, int);
+void printw(char *, int, int);
+void srplace(char *, int, char *, char *, int);
+
+//prototypes for functions to handle required functionality
+int count_words(char *buff, int len, int str_len) {
+ int word_count = 0;
+ int in_word = 0;
+
+ for (int i = 0; i < str_len; i++) {
+ if (*(buff + i) != ' ') {
+ if (!in_word) {
+ in_word = 1;
+ word_count++;
+ }
+ } else {
+ in_word = 0;
+ }
+ }
+
+ return word_count;
+}
+
+int setup_buff(char *buff, char *user_str, int len) {
+ char *src = user_str;
+ char *dest = buff;
+ int count = 0;
+ int space_flag = 0;
+ while (*src != '\0' && count < len) {
+ if (*src == ' ' || *src == '\t') {
+ if (!space_flag) {
+ *dest++ = ' ';
+ count++;
+ space_flag = 1;
+ }
+ } else {
+ *dest++ = *src;
+ count++;
+ space_flag = 0;
+ }
+ src++;
+ }
+ if (*src != '\0') {
+ return -1;
+ }
+ while (count < len) {
+ *dest++ = '.';
+ count++;
+ }
+ return count;
+}
+
+void print_buff(char *buff, int len) {
+ printf("Buffer: [");
+ for (int i = 0; i < len; i++) {
+ putchar(*(buff + i));
+ }
+ printf("]\n");
+}
+
+void usage(char *exename) {
+ printf("usage: %s [-h|c|r|w|x] \"string\" [other args]\n", exename);
+}
+
+void reverse(char *buff, int len, int str_len) {
+ char *start = buff;
+ char *end = buff + str_len - 1;
+ char temp;
+
+ while (start < end) {
+ temp = *start;
+ *start = *end;
+ *end = temp;
+ start++;
+ end--;
+ }
+}
+
+void printw(char *buff, int len, int str_len) {
+ int word_index = 1;
+ int word_length = 0;
+
+ printf("Word Print\n----------\n");
+
+ for (int i = 0; i < str_len; i++) {
+ char current_char = *(buff + i);
+ if ((current_char >= 'A' && current_char <= 'Z') ||
+ (current_char >= 'a' && current_char <= 'z') ||
+ (current_char >= '0' && current_char <= '9')) {
+
+ if (word_length == 0) {
+ printf("%d. ", word_index);
+ }
+ putchar(current_char);
+ word_length++;
+ } else if (current_char == ' ' && word_length > 0) {
+ printf("(%d)\n", word_length);
+ word_index++;
+ word_length = 0;
+ }
+ }
+ if (word_length > 0) {
+ printf(" (%d)\n", word_length);
+ }
+
+ printf("\nNumber of words returned: %d\n", word_index);
+}
+
+
+
+void srplace(char *buff, int len, char *old, char *new, int str_len) {
+ char temp[BUFFER_SZ];
+ char *src = buff, *dest = temp;
+ int old_len = strlen(old), new_len = strlen(new);
+ int replaced = 0;
+
+ while (*src != '\0' && (dest - temp) < BUFFER_SZ) {
+ if (strncmp(src, old, old_len) == 0) {
+ if ((dest - temp) + new_len > BUFFER_SZ) {
+ break; // Prevent overflow
+ }
+ strncpy(dest, new, new_len);
+ src += old_len;
+ dest += new_len;
+ replaced = 1;
+ } else {
+ *dest++ = *src++;
+ }
+ }
+
+ while ((dest - temp) < BUFFER_SZ) {
+ *dest++ = '.';
+ }
+
+ if (replaced) {
+ memcpy(buff, temp, BUFFER_SZ);
+ } else {
+ printf("Not Implemented!\n");
+ exit(1);
+ }
+}
+
+int main(int argc, char *argv[]) {
+
+ char *buff; //placehoder for the internal buffer
+ char *input_string; //holds the string provided by the user on cmd line
+ char opt; //used to capture user option from cmd line
+ int rc; //used for return codes
+ int user_str_len; //length of user supplied string
+
+ //TODO: #1. WHY IS THIS SAFE, aka what if arv[1] does not exist?
+ //This is done to make that the command has the right syntax and all the minimal arguments
+ //needed for the subsequent operations to run with valid inputs, or to specify the type of error
+ //so the user may rectify it and find the right command that will work.
+ if ((argc < 2) || (*argv[1] != '-')){
+ usage(argv[0]);
+ exit(1);
+ }
+
+ opt = (char)*(argv[1]+1);
+
+ //handle the help flag and then exit normally
+ if (opt == 'h'){
+ usage(argv[0]);
+ exit(0);
+ }
+
+ //WE NOW WILL HANDLE THE REQUIRED OPERATIONS
+
+ //TODO: #2 Document the purpose of the if statement below
+ //It ensures that the user enters a command with at least one flag and two required parameters
+ //to proceed. Otherwise, an error will occur, and the syntax will assist them enter the right command.
+ if (argc < 3){
+ usage(argv[0]);
+ exit(1);
+ }
+
+ input_string = argv[2]; //capture the user input string
+
+ //TODO: #3 Allocate space for the buffer using malloc and
+ // handle error if malloc fails by exiting with a
+ // return code of 99
+ buff = (char *)malloc(BUFFER_SZ);
+ if (buff == NULL) {
+ exit(99);
+ }
+
+ user_str_len = setup_buff(buff, input_string, BUFFER_SZ);
+ if (user_str_len < 0) {
+ printf("Error setting up buffer\n");
+ free(buff);
+ exit(2);
+ }
+
+ switch (opt) {
+ case 'c':
+ rc = count_words(buff, BUFFER_SZ, user_str_len); //you need to implement
+ if (rc < 0){
+ printf("Error counting words, rc = %d", rc);
+ exit(2);
+ }
+ printf("Word Count: %d\n", rc);
+ break;
+ case 'r':
+ reverse(buff, BUFFER_SZ, user_str_len);
+ break;
+ case 'w':
+ printw(buff, BUFFER_SZ, user_str_len);
+ break;
+
+ case 'x':
+ if (argc < 5) {
+ usage(argv[0]);
+ free(buff);
+ exit(1);
+ }
+ srplace(buff, BUFFER_SZ, argv[3], argv[4], user_str_len);
+ break;
+ default:
+ usage(argv[0]);
+ free(buff);
+ exit(1);
+ }
+
+ //TODO: #6 Dont forget to free your buffer before exiting
+ print_buff(buff, BUFFER_SZ);
+ free(buff);
+ exit(0);
+}
+
+//TODO: #7 Notice all of the helper functions provided in the
+// starter take both the buffer as well as the length. Why
+// do you think providing both the pointer and the length
+// is a good practice, after all we know from main() that
+// the buff variable will have exactly 50 bytes?
+//
+// Both the pointer and the length must be provided since this
+// will enable the function to monitor the buffer's length during and after each
+// modification step to prevent overflow and to set up the buffer once the string
+// operation is finished (ensuring that it always contains exactly 50 bytes).
\ No newline at end of file
--
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