day7 coding: 变量存储、预处理

day7/d10/a.c

@@ -0,0 +1,11 @@
+#include "a.h"
+
+int sum(int a, int b)
+{
+    return a + b;
+}
+
+int sub(int a, int b)
+{
+    return a - b;
+}

day7/d10/a.h

@@ -0,0 +1,4 @@
+#include <stdio.h>
+
+extern int sum(int, int);
+extern int sub(int, int);

day7/d10/main.c

@@ -0,0 +1,9 @@
+#include "./a.h"
+
+int main(int argc, char const *argv[])
+{
+    int ret = sum(100, 200);
+    printf("100 + 200 = %d\n", ret);
+    printf("ret - 60 = %d\n", sub(ret, 60));
+    return 0;
+}