Basic calculator

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>

Author: begeekmyfriend

224_basic_calculator/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test calculator.c

224_basic_calculator/calculator.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+static int calculator(char *s)
+{
+    int n;
+    int pos1 = 0;
+    int pos2 = 0;
+    int *nums = malloc(1000 * sizeof(int));
+    char *signs = malloc(1000 * sizeof(char));
+
+    nums[pos1++] = 0;
+    while (*s != '\0') {
+        switch (*s) {
+        case '+':
+        case '-':
+        case '(':
+            signs[pos2++] = *s;
+            break;
+        case ')':
+            --pos2;
+            if (pos1 >= 2 && pos2 > 0 && signs[pos2 - 1] != '(') {
+                n = nums[--pos1];
+                int a = nums[--pos1];
+                if (signs[--pos2] == '+') {
+                    n = a + n;
+                } else {
+                    n = a - n;
+                }
+            }
+            nums[pos1++] = n;
+            break;
+        case ' ':
+            break;
+        default:
+            n = 0;
+            while(*s >= '0' && *s <= '9') {
+                n = n * 10 + (*s - '0');
+                s++;
+            }
+            s--;
+
+            if (pos1 >= 2 && signs[pos2 - 1] != '(' && signs[pos2 - 1] != '(') {
+                int a = nums[--pos1];
+                if (signs[--pos2] == '+') {
+                    n = a + n;
+                } else {
+                    n = a - n;
+                }
+            }
+            nums[pos1++] = n;
+            break;
+        }
+        s++;
+    }
+
+    return n;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: ./test string\n");
+        exit(-1);
+    }
+    printf("%d\n", calculator(argv[1]));
+    return 0;
+}

227_basic_calculator_ii/Makefile

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+all:
+	gcc -O2 -o test calculator.c

227_basic_calculator_ii/calculator.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+static int calculator(char *s)
+{
+    int n;
+    int pos1 = 0;
+    int pos2 = 0;
+    int *nums = malloc(100 * sizeof(int));
+    char *signs = malloc(100 * sizeof(char));
+
+    nums[pos1++] = 0;
+    while (*s != '\0') {
+        switch (*s) {
+        case '+':
+        case '-':
+            if (pos1 >= 3) {
+                int b = nums[pos1 - 1];
+                int a = nums[pos1 - 2];
+                if (signs[--pos2] == '+') {
+                    nums[pos1 - 2] = a + b;
+                } else {
+                    nums[pos1 - 2] = a - b;
+                }
+                pos1--;
+            }
+        case '*':
+        case '/':
+            signs[pos2++] = *s;
+            break;
+        case ' ':
+            break;
+        default:
+            n = 0;
+            while(*s >= '0' && *s <= '9') {
+                n = n * 10 + (*s - '0');
+                s++;
+            }
+            s--;
+
+            if (pos1 >= 2 && signs[pos2 - 1] != '+' && signs[pos2 - 1] != '-') {
+                int a = nums[--pos1];
+                if (signs[--pos2] == '*') {
+                    n = a * n;
+                } else {
+                    n = a / n;
+                }
+            }
+            nums[pos1++] = n;
+            break;
+        }
+        s++;
+    }
+
+    while (pos2 > 0) {
+        n = nums[--pos1];
+        int a = nums[--pos1];
+        if (signs[--pos2] == '+') {
+            n = a + n;
+        } else {
+            n = a - n;
+        }
+    }
+    return n;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: ./test string\n");
+        exit(-1);
+    }
+    printf("%d\n", calculator(argv[1]));
+    return 0;
+}