Finished exercise 3-2. Starting 3.5

ch_03/exercise_03-02/main.c

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+/*
+ *
+ * Exercise 3-2. Write a function escape(s,t) that converts characters like
+ * newline and tab into visible escape sequences like '\n' and '\t' as it
+ * copies the string t to s. Use a switch. Write a function for the other
+ * direction as well, converting escape sequences into real characters.
+ *
+ * Author: Kun Deng
+ */
+
+#include <stdio.h>
+
+#define ARRAY_SIZE 10
+#define BUFFER_SIZE (ARRAY_SIZE * 2)
+
+// Copies string t to s but the escape sequences
+// will be visible
+void escape(char *s, char *t);
+// Copies string t to s but the escape sequences
+// will be their real characters
+void ensnare(char *s, char *t);
+
+
+int main()
+{
+    printf("Enter characters:\n");
+
+    char unproccessed[ARRAY_SIZE];
+    char escaped[BUFFER_SIZE];
+    char ensared[ARRAY_SIZE];
+    char c;
+    int i;
+
+    for (i = 0; i != ARRAY_SIZE; ++i)
+    {
+        c = getchar();
+
+        if (c == EOF)
+        {
+            --i;
+            continue;
+        }
+
+        unproccessed[i] = c;
+    }
+
+    unproccessed[i] = '\0';
+
+    printf("\n\nUnproccessed string: %s\n", unproccessed);
+
+    escape(escaped, unproccessed);
+    printf("\n\nEscaped sequences replaced string: %s\n", escaped);
+
+    ensnare(ensared, escaped);
+    printf("\n\nEscaped sequences returned string: %s\n", ensared);
+
+    return 0;
+}
+
+
+void escape(char *s, char *t)
+{
+    int j = 0;
+    char c;
+
+    for (int i = 0; ((c = t[i])) != '\0'; ++i, ++j)
+    {
+        switch (c)
+        {
+        case '\n':
+            s[j++] = '\\';
+            s[j] = 'n';
+            break;
+        case '\t':
+            s[j++] = '\\';
+            s[j] = 't';
+            break;
+        default:
+            s[j] = c;
+            break;
+        }
+    }
+
+    s[j] = '\0';
+}
+
+void ensnare(char *s, char *t)
+{
+    int j = 0;
+    // If one that means the previous character was the beginning of an escape
+    // sequence
+    int escape_found = 0;
+    char c;
+    char rr[] = "thecarinspace\0";
+
+    for (int i = 0; ((c = t[i])) != '\0'; ++i, ++j)
+    {
+        switch (c)
+        {
+        case '\\':
+            escape_found = 1;
+            --j;
+            break;
+        case 'n':
+            s[j] = (escape_found == 1) ? 10 : c;
+            escape_found = 0;
+            break;
+        case 't':
+            s[j] = (escape_found == 1) ? 9 : c;
+            escape_found = 0;
+            break;
+        default:
+            s[j] = c;
+            break;
+        }
+    }
+
+    s[j] = '\0';
+}