Initial commit: C language learning code

课上代码练习/1.1.3/num_sum.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+int main()
+{ 
+    int sign = 1;
+    int n;
+    printf("ÇëÊäÈën: ");
+    scanf("%d", &n);
+    double deno = 2.0, sum = 1.0, term;
+
+    while (deno <= n)
+    {    
+        sign = -sign;
+        term = sign / deno;
+        sum = sum + term;
+        deno = deno + 1;
+    }
+    printf("%f\n", sum);
+
+    return 0;
+}