完成了第九章1-5题的编写，运行无误。

9_1.c

+#include<stdio.h>
+void exchange(int *pa,int *pb)
+{
+    int t;
+    t = *pa; *pa = *pb; *pb = t;
+}
+int main()
+{
+    int a, b, c,*pa,*pb,*pc;
+    scanf("%d,%d,%d", &a,&b,&c);
+    pa = &a; pb = &b; pc = &c;
+    if(a>b) exchange(pa,pb);
+    if(a>c) exchange(pa,pc);
+    if(b>c) exchange(pb,pc);
+    printf("%d\t%d\t%d\n",a,b,c);
+    return 0;
+}
\ No newline at end of file

9_2.c

+#include <stdio.h>
+
+int main()
+{
+    int a[10], *p=a;
+    for(int i=0; i<10; i++) scanf("%d",&a[i]);
+    for(int i=0; i<10; i++) if(*p>a[i]) p = &a[i];
+    for(int i=0; i<10; i++) printf("%d\t",a[i]);
+    printf("\nmin = %d",*p);
+    return 0;
+}
\ No newline at end of file

9_3.c

+#include <stdio.h>
+
+int fsum(int *array,int n)
+{
+    int i,s=0;
+
+    for(i=0;i<n;i++)
+        s += array[i];
+        return (s);
+}
+int main()
+{
+    int a[15] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 ,12, 13, 14, 15};
+    int shead, stail;
+    shead = fsum(a,10);
+    stail = fsum(&a[5], 10);
+    printf("%d,%d\n",shead,stail);
+    return 0;
+}
\ No newline at end of file

9_4.c

+#include <stdio.h>
+
+void moveLeft(int *a, int n)
+{
+    int *p = &a[n-1],b = a[n-1];
+    while(p != a)
+    {
+        int t;
+        t = b;
+        b = *(p-1);
+        *(p---1) = t;
+    }
+    a[n-1] = b;
+}
+void rotateLeft(int *a, int n, int k)
+{
+    int i;
+    for(i = 0; i < k; i++) moveLeft(a,n);
+}
+int main()
+{
+    int a[]={ 2, 3, 4, 5, 6, 7, 8, 9 };
+    int i, k;
+    printf("input k please: \n");
+    scanf("%d",&k);
+    for(i = 0; i < 8; i++) printf("%d\t",a[i]);
+    printf("\n");
+    rotateLeft(a,8,k);
+    for(i = 0; i < 8; i++) printf("%d\t",a[i]);
+}
\ No newline at end of file

9_5.c

+#include <stdio.h>
+
+void statistic( int *a, int n, int *posinum_ptr, int *neganum_ptr)
+{
+    int *p = a;
+    while(p != a+n)
+    {
+        if(*p > 0) (*posinum_ptr)++;
+        if(*p < 0) (*neganum_ptr)++;
+        p++;
+    }
+    
+}
+int main()
+{
+    int a[10];
+    int i,posi_num,nega_num;
+    for(i=0; i<10; i++) scanf("%d", &a[i]);
+    statistic(a, 10, &posi_num, &nega_num);
+    printf("posi_num: %d, nega_num: %d",posi_num,nega_num);
+}
\ No newline at end of file

C语言课程设计/C语言课程设计.vcxproj

@@ -24,6 +24,7 @@
     <ProjectGuid>{2e2cb14a-5141-4136-9b14-56a832c31276}</ProjectGuid>
     <RootNamespace>C语言课程设计</RootNamespace>
     <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+    <ProjectName>visualstudio2019</ProjectName>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">