Exercise 5.10main

3 files changed, 195 insertions, 24 deletions

diff --git a/ex5-10.c b/ex5-10.c
new file mode 100644
index 0000000..c4afccd
--- /dev/null
+++ b/ex5-10.c
@@ -0,0 +1,113 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+#define NUMBER '0'
+#define MAXLINE 1000
+#define MAXVAL 100
+
+int getop(char[]);
+
+void push(double);
+double pop(void);
+void clear(void);
+double peek(void);
+
+// Naïve implementation of remainder operation
+double frem(double f1, double f2) {
+    return f1 - (f2 * (int)(f1 / f2));
+}
+
+/**
+ * Reverse polish notation calculator
+ */
+int main(int argc, char* argv[]) {
+    if (argc <= 1) {
+        fprintf(stderr, "Usage: rpol EXPR...");
+        return 1;
+    }
+    argv++; // Skip program name
+    double op2;
+    for (; *argv != NULL; argv++) {
+        char* tok = *argv;
+        int type = getop(tok);
+        switch (type) {
+            case NUMBER:
+                push(atof(tok));
+                break;
+            case '+':
+                push(pop() + pop());
+                break;
+            case '*':
+                push(pop() * pop());
+                break;
+            case '-':
+                op2 = pop();
+                push(pop() - op2);
+                break;
+            case '/':
+                op2 = pop();
+                if (op2 != 0.0)
+                    push(pop() / op2);
+                else
+                    printf("error: zero division attempted!\n");
+                break;
+            case '%':
+                op2 = pop();
+                if (op2 != 0.0) 
+                    push(frem(pop(), op2));
+                else 
+                    printf("error: zero division attempted!\n");
+                break;
+            case '~':
+                clear();
+                break;
+            default:
+                printf("unknown command %s\n", tok); // Just ignore it?
+                break;
+        }
+    }
+
+    printf("\t%.8g\n", pop());
+    return 0;
+}
+
+int sp; // Stack position
+double val[MAXVAL]; // Value stack
+void push(double f) {
+    if (sp < MAXVAL) {
+        val[sp++] = f;
+    } else {
+        printf("error, stack full\n");
+    }
+}
+
+double pop(void) {
+    if (sp >= 0) {
+        return val[--sp];
+    } else {
+        printf("error, empty stack\n");
+        return 0.0;
+    }
+}
+
+double peek(void) {
+    if (sp >= 0) {
+        return val[sp-1];
+    } else {
+        printf("error, empty stack\n");
+        return 0.0;
+    }   
+}
+
+void clear(void) {
+    sp = 0;
+}
+
+int getop(char s[]) {
+    char c = s[0];
+    if (!isdigit(c) && c != '.') 
+        return c;
+    return NUMBER;
+}
diff --git a/ex5-7.c b/ex5-7.c
index 2d277ad..1457410 100644
--- a/ex5-7.c
+++ b/ex5-7.c
@@ -3,25 +3,25 @@
 
 // An extremely simple allocation system.
 // Memory must be freed in the reverse order it was allocated.
-#define ALLOCSIZE 10000
-
-static char allocbuf[ALLOCSIZE];
-static char *allocp = allocbuf;
-
-char *alloc(int n) {
-    if (allocbuf + ALLOCSIZE - allocp >= n) {
-        allocp += n;
-        return allocp - n;
-    } else {
-        return NULL;
-    }
-}
-
-void afree(char *p) {
-    if (p >= allocbuf && p < allocbuf + ALLOCSIZE) {
-        allocp = p;
-    }
-}
+// #define ALLOCSIZE 10000
+
+// static char allocbuf[ALLOCSIZE];
+// static char *allocp = allocbuf;
+
+// char *alloc(int n) {
+//     if (allocbuf + ALLOCSIZE - allocp >= n) {
+//         allocp += n;
+//         return allocp - n;
+//     } else {
+//         return NULL;
+//     }
+// }
+
+// void afree(char *p) {
+//     if (p >= allocbuf && p < allocbuf + ALLOCSIZE) {
+//         allocp = p;
+//     }
+// }
 
 #define MAXLINES 5000
 
@@ -47,7 +47,7 @@ int main() {
 #define MAXLEN 1000
 
 int z_getline(char*, int);
-char* alloc(int);
+// char* alloc(int);
 
 int readlines(char* lineptr[], int maxlines) {
     int len; 
@@ -71,9 +71,10 @@ void writelines(char* lineptr[], int nlines) {
         printf("%s\n", lineptr[i]);
 }
 
-void qsort(char* v[], int left, int right) {
-    int i, last;
-    void swap(char* v[], int i, int j);
+void swap(char* v[], int i, int j);
+
+void qsort(char* v[], const int left, const int right) {
+    int i, last;    
     if (left >= right) {
         return;
     }
@@ -95,7 +96,6 @@ void swap(char* v[], int i, int j) {
     v[j] = temp;
 }
 
-
 /* getline:  read a line into s, return length */
 int z_getline(char s[], int lim) {
     int c, i;
diff --git a/ex5-8.c b/ex5-8.c
new file mode 100644
index 0000000..1f74a19
--- /dev/null
+++ b/ex5-8.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#define NDEBUG
+#include <assert.h>
+
+static char daytab[2][13] = {
+    {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
+    {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
+};
+
+/* day_of_year:  set day of year from month & day */
+int day_of_year(int year, int month, int day)
+{
+    assert(month >= 1);
+    assert(month <= 12);
+
+    int i, leap;
+
+    leap = (year%4 == 0 && year%100 != 0) || year%400 == 0;
+
+    assert(day >= 1);
+    assert(day <= *(*(daytab+leap) + month));
+
+    for (i = 1; i < month; i++)
+        day += *(*(daytab+leap) + i);
+    return day;
+}
+
+/* month_day:  set month, day from day of year */
+void month_day(int year, int yearday, int *pmonth, int *pday)
+{
+    int i, leap;
+
+    leap = (year%4 == 0 && year%100 != 0) || year%400 == 0;
+
+    assert(yearday >= 1);
+    assert(yearday <= (leap ? 366 : 365));
+    
+    for (i = 1; yearday > *(*(daytab+leap)+i); i++)
+        yearday -= *(*(daytab+leap)+i);
+    *pmonth = i;
+    *pday = yearday;
+}
+
+int main(void) {
+    // Add error checking eh
+    int doy, dom, month;
+    doy = day_of_year(2022, 2, 8);
+    month_day(2022, doy, &month, &dom);
+
+    printf("2022-02-08 doy=%d month=%d dom=%d\n", doy, month, dom);
+
+    doy = day_of_year(2022, 0, 8);
+    doy = day_of_year(2022, 13, 8);
+    doy = day_of_year(2022, 12, 0);
+    doy = day_of_year(2022, 12, 32);
+    doy = day_of_year(2022, 2, 29);
+    doy = day_of_year(2024, 2, 29); // This one is ok
+}
\ No newline at end of file