Add stringfun.c and Makefile

stringfun.c

+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+#define BUFFER_SZ 50
+
+// Prototypes
+void usage(char *);
+void print_buff(char *);
+int setup_buff(char *, char *, int);
+int count_words(char *, int);
+void reverse_buffer(char *);
+void print_words(char *);
+int search_replace(char *, char *, char *);
+
+// Helper function: Clean spaces
+void clean_spaces(char *buff, int *len) {
+    char *src = buff, *dst = buff;
+    int in_space = 0;
+
+    while (*src) {
+        if (isspace(*src)) {
+            if (!in_space) {
+                *dst++ = ' ';
+                in_space = 1;
+            }
+        } else {
+            *dst++ = *src;
+            in_space = 0;
+        }
+        src++;
+    }
+    // Remove trailing space
+    if (dst > buff && isspace(*(dst - 1))) {
+        dst--;
+    }
+
+    *dst = '\0';
+    *len = strlen(buff);
+}
+
+// Setup buffer
+int setup_buff(char *buff, char *user_str, int len) {
+    if (!buff || !user_str) {
+        return -1;
+    }
+    int user_str_len = strlen(user_str);
+    if (user_str_len >= len) {
+        memcpy(buff, user_str, len - 1);
+        buff[len - 1] = '\0';
+    } else {
+        strcpy(buff, user_str);
+        memset(buff + user_str_len, '.', len - user_str_len);
+    }
+    return strlen(buff);
+}
+
+// Print buffer
+void print_buff(char *buff) {
+    printf("Buffer:  [");
+    for (int i = 0; i < BUFFER_SZ; i++) {
+        putchar(buff[i] ? buff[i] : '.');
+    }
+    printf("]\n");
+}
+
+// Word counting
+int count_words(char *buff, int str_len) {
+    if (!buff || str_len <= 0) {
+        return -1;
+    }
+    clean_spaces(buff, &str_len);
+    int word_count = 0, in_word = 0;
+
+    for (int i = 0; i < str_len; i++) {
+        if (!isspace(buff[i])) {
+            if (!in_word) {
+                word_count++;
+                in_word = 1;
+            }
+        } else {
+            in_word = 0;
+        }
+    }
+    return word_count;
+}
+
+// Reverse buffer
+void reverse_buffer(char *buff) {
+    if (!buff) return;
+    int end = strlen(buff) - 1;
+    for (int i = 0; i < end; i++, end--) {
+        char temp = buff[i];
+        buff[i] = buff[end];
+        buff[end] = temp;
+    }
+}
+
+// Print words
+void print_words(char *buff) {
+    int word_count = 0;
+    printf("Word Print\n----------\n");
+    char *token = strtok(buff, " ");
+    while (token) {
+        printf("%d. %s(%ld)\n", ++word_count, token, strlen(token));
+        token = strtok(NULL, " ");
+    }
+    printf("\nNumber of words returned: %d\n", word_count);
+}
+
+// Search and replace
+int search_replace(char *buff, char *old, char *new_str) {
+    char temp[BUFFER_SZ];
+    char *pos, *curr = buff;
+    int old_len = strlen(old), new_len = strlen(new_str);
+    int temp_len = 0;
+
+    if (!buff || !old || !new_str) return -1;
+
+    while ((pos = strstr(curr, old))) {
+        if (temp_len + (pos - curr) + new_len >= BUFFER_SZ) break;
+
+        memcpy(temp + temp_len, curr, pos - curr);
+        temp_len += pos - curr;
+
+        memcpy(temp + temp_len, new_str, new_len);
+        temp_len += new_len;
+
+        curr = pos + old_len;
+    }
+
+    if (temp_len + strlen(curr) >= BUFFER_SZ) return -1;
+
+    strcpy(temp + temp_len, curr);
+    strncpy(buff, temp, BUFFER_SZ - 1);
+    buff[BUFFER_SZ - 1] = '\0';
+
+    return 0;
+}
+
+// Usage
+void usage(char *exename) {
+    printf("usage: %s [-h|c|r|w|x] \"string\" [other args]\n", exename);
+}
+
+// Main function
+int main(int argc, char *argv[]) {
+    char *buff = (char *)malloc(BUFFER_SZ * sizeof(char));
+    if (!buff) {
+        fprintf(stderr, "Error: Memory allocation failed\n");
+        exit(99);
+    }
+
+    if ((argc < 2) || (*argv[1] != '-')) {
+        usage(argv[0]);
+        free(buff);
+        exit(1);
+    }
+
+    char opt = argv[1][1];
+    if (opt == 'h') {
+        usage(argv[0]);
+        free(buff);
+        exit(0);
+    }
+
+    if (argc < 3) {
+        usage(argv[0]);
+        free(buff);
+        exit(1);
+    }
+
+    char *input_string = argv[2];
+    int user_str_len = setup_buff(buff, input_string, BUFFER_SZ);
+
+    if (user_str_len < 0) {
+        fprintf(stderr, "Error setting up buffer\n");
+        free(buff);
+        exit(2);
+    }
+
+    switch (opt) {
+        case 'c':
+            printf("Word Count: %d\n", count_words(buff, user_str_len));
+            break;
+        case 'r':
+            reverse_buffer(buff);
+            break;
+        case 'w':
+            print_words(buff);
+            break;
+        case 'x':
+            if (argc < 5) {
+                usage(argv[0]);
+                free(buff);
+                exit(1);
+            }
+            if (search_replace(buff, argv[3], argv[4]) != 0) {
+                printf("Not Implemented!\n");
+                free(buff);
+                exit(1);
+            }
+            break;
+        default:
+            usage(argv[0]);
+            free(buff);
+            exit(1);
+    }
+
+    print_buff(buff);
+    free(buff);
+    exit(0);
+}
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