diff --git a/step_6_update.c b/step_6_update.c
new file mode 100644
index 0000000..d57454e
--- /dev/null
+++ b/step_6_update.c
@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#define NAME 20
+#define SIZE 3
+struct student
+{
+    int id;
+    int class;
+    char name[NAME];
+    float score_math;
+    float score_phi;
+    float score_eng;
+    bool ismodified;
+};
+
+
+void update(struct student a[],int count){
+    struct student temp;
+    scanf("%d %d %s %f %f %f",&temp.id,&temp.class,&temp.name,&temp.score_math,&temp.score_phi,&temp.score_eng);
+    for(int i = 0;i<count;i++){
+        if(a[i].id == temp.id){
+            a[i] = temp;
+            a[i].ismodified = true;
+            break;
+        }
+    }   
+}
+
+void sort(struct student a[],int count){
+    struct student temp;
+    for(int i = 0;i < count-1;i++){
+        for(int j = i+1;j<count-1;j++){
+            if(a[j].class > a[j+1].class){
+                temp = a[j];
+                a[j] = a[j+1];
+                a[j+1] = temp;
+            }
+        }
+    }
+    for (int m = 0; m < count-1; m++) {
+    for (int n = m + 1; n < count-1; n++) {
+        if (a[n].class == a[n+1].class) {
+            float sum1 = a[n].score_math + a[n].score_phi + a[n].score_eng;
+            float sum2 = a[n+1].score_math + a[n+1].score_phi + a[n+1].score_eng;
+            if (sum1 < sum2 || (sum1 == sum2 && a[m].id > a[n].id)) {
+                struct student temp = a[n];
+                a[n] = a[n+1];
+                a[n+1] = temp;
+            }
+        }
+    }
+}
+}
+void printgrade(struct student a[],int count){
+    for(int i = 0;i<count;i++){
+        if(i == 0)
+        printf("%d %d %s %.1f %.1f %.1f",a[i].class,a[i].id,a[i].name,a[i].score_math,a[i].score_phi,a[i].score_eng);
+        else{
+            if(a[i].class == a[i-1].class){
+                printf("   %d %s %.1f %.1f %.1f",a[i].id,a[i].name,a[i].score_math,a[i].score_phi,a[i].score_eng);
+            }
+            else{
+                printf("%d %d %s %.1f %.1f %.1f",a[i].class,a[i].id,a[i].name,a[i].score_math,a[i].score_phi,a[i].score_eng);
+            }
+        }
+        if(a[i].ismodified){
+            printf(" modified\n");
+        }
+        else{
+            printf("\n");
+        }
+    }
+}
+int main(){
+    struct student grade[SIZE]={
+        {10001,11,"Zhang",99.5,88.5,89.5,false},
+        {10002,12,"Yang",77.9,56.5,87.5,false},
+        {10003,11,"Liang",92.5,99.0,60.5,false}
+    };
+    int count = SIZE;
+    update(grade,count);
+    sort(grade,count);
+    printgrade(grade,count);
+    return 0;
+}
\ No newline at end of file