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';
+}

ch_03/switch/main.c

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+/*
+ *
+ * The program demonstrates the use of the switch statement while counting
+ * the occurrences of digits, white spaces (including actual white space,
+ * new line, and a tab character), and other types of characters
+ *
+ * Author: Kun Deng
+ */
+
+#include <stdio.h>
+
+
+#define ARRAY_SIZE 13
+
+int main()
+{
+    int c, white_space_count, other_character_count;
+    int digit_count[ARRAY_SIZE];
+
+    white_space_count = other_character_count = 0;
+
+    for (int i = 0; i < ARRAY_SIZE; ++i)
+    {
+        digit_count[i] = 0;
+    }
+
+    while ((c = getchar()) != EOF)
+    {
+        switch (c)
+        {
+        case '0':
+        case '1':
+        case '2':
+        case '3':
+        case '4':
+        case '5':
+        case '6':
+        case '7':
+        case '8':
+            // If no break statement is provided in a case then
+            // the code can continue to execute other cases where
+            // the expression matches the case.
+        case '9':
+            ++digit_count[c - '0'];
+            // Break statements causes the control flow of the program
+            // to exit out of the block of code. In this case the
+            // break statement will cause the control flow to exit
+            // from the switch statement
+            break;
+        case ' ':
+        case '\n':
+        case '\t':
+            ++white_space_count;
+            break;
+        default:
+            // Good practice to have a default case and have a break statement.
+            // Just in case more cases are added to the future
+            ++other_character_count;
+            break;
+        }
+    }
+
+    printf("Digits =");
+
+    for (int i = 0; i < ARRAY_SIZE; ++i)
+    {
+        printf(" %d", digit_count[i]);
+    }
+
+    printf(", white space = %d, other = %d\n", 
+            white_space_count, other_character_count);
+
+
+    return 0;
+}