# include & lt; stdio.h> 
# include 

/* structure definition students */

Struct Student 
{
Char ID [20]; 
Char Name [20]. 
Float Mark1; 
Float Mark2; 
Float Mark3. 
Float Mark4; 
Float Mark5; 
Float business; 
}; 


/* array declaration students and student number */

Struct Student students [1000]. 
int num=0; 



/* averaging */

Float Avg (struct Student stu) 
{
Return ((stu. Mark1 + stu. Mark2 + stu. Mark3 + stu. Mark4 + stu. Mark5)/5); 
} 



Returns an array subscript *//* by student number 

Int Student_SearchByIndex (char id []) 
{
int i; 
for (i=0; I{
If (STRCMP (students [I] ID, ID)==0) 
{
return i; 
} 
} 
return -1; 
} 



Returns an array subscript *//* by name 

Int Student_SearchByName (char name []) 
{
int i; 
for (i=0; I{
If (STRCMP (students [I]. Name, Name)==0) 
{
return i; 
} 
} 
return -1; 
} 



/* shows a single student record */

Void Student_DisplaySingle (int index) 
{
Printf (" % s % 10 s 8 8 8 s % % s % s % s \ n ", "student id", "name", "grade 1", "grade 2", "three grade", "grade 4", "grade 5," "gpa"); 
Printf (" -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - \ n "); 
Printf (" % s % s % 8.2 f % 8.2 f % 8.2 f % 10.2 f \ n ", students [index]. ID, students [index]. Name, 
Students [index]. Mark1, students [index] Mark2, students [index] Mark3, students [index] Mark4, students [index] Mark5, students [index] business); 
} 



/* insert student information */

Void Student_Insert () 
{
While (1) 
{
Printf (" please enter the student id: "); 
The scanf (" % s ", & amp; Students (num). ID); 
getchar(); 

Printf (" please input your name: "); 
The scanf (" % s ", & amp; Students (num). Name); 
getchar(); 

Printf (" please enter the grade 1: "); 
The scanf (" % f ", & amp; Students [r]. Num Mark1); 
getchar(); 

Printf (" please enter the grade 2: "); 
The scanf (" % f ", & amp; Students [r]. Num Mark2); 
getchar(); 

Printf (" please enter the grade 3: "); 
The scanf (" % f ", & amp; Students [r]. Num Mark3); 
getchar(); 

Printf (" please enter the grade 4: "); 
The scanf (" % f ", & amp; Students [r]. Num Mark4); 
getchar(); 

Printf (" please enter the grade 5: "); 
The scanf (" % f ", & amp; Students [r]. Num Mark5); 
getchar(); 


Students [num] business=Avg (students (num)); 
num++; 

Printf (" whether to continue? (y/n) "); 
If (getchar ()=='n') 
{
break; 
} 
} 
} 



/* * modify the students information/

Void Student_Modify () 

{

//float mark1, mark2 mark3; 

While (1) 
{
Char id [20]; 
Int index; 
Printf (" please input to modify the student's student id: "); 
The scanf (" % s ", & amp; id); 
getchar(); 
The index=Student_SearchByIndex (id); 
If (index==1) 
{
Printf (" the student does not exist! \n"); 
} 
The else 
{
Printf (" do you want to modify the information of students is: \ n "); 
Student_DisplaySingle (index); 
Printf (" please enter a new value - \ n "); 
Printf (" please enter the student id: "); 
The scanf (" % s ", & amp; Students [index]. ID); 
getchar(); 
Printf (" please input your name: "); 
The scanf (" % s ", & amp; Students [index]. Name); 
getchar(); 
Printf (" please enter the grade 1: "); 
The scanf (" % f ", & amp; Students [index] Mark1); 
getchar(); 
Printf (" please enter the grade 2: "); 
The scanf (" % f ", & amp; Students [index] Mark2); 
getchar(); 
Printf (" please enter the grade 3: "); 
The scanf (" % f ", & amp; Students [index] Mark3); 
getchar(); 
Printf (" please enter the grade 4: "); 
The scanf (" % f ", & amp; Students [index] Mark4); 
getchar(); 
Printf (" please enter the grade 5: "); 
The scanf (" % f ", & amp; Students [index] Mark5); 
getchar(); 
Students [index]. Business=Avg (students [index]); 
} 
Printf (" whether to continue? (y/n) "); 
If (getchar ()=='n') 
{
break; 
} 
} 
} 



/* */delete student information 

Void Student_Delete () 

{

int i; 
While (1) 
{
Char id [20]; 
Int index; 
Printf (" please enter the student's student id: to delete "); 
The scanf (" % s ", & amp; id); 
getchar(); 
The index=Student_SearchByIndex (id); 
If (index==1) 
{
Printf (" the student does not exist! \n"); 
} 
The else 
{
Printf (" you want to delete student information for: \ n "); 
Student_DisplaySingle (index); 
Printf (" really want to delete? (y/n) "); 
If (getchar ()=='y') 
{
For (I=index; I{
Students [I]=students [I + 1);//all the objects behind forward 
} 
Num -; 
} 
getchar(); 
} 
Printf (" whether to continue? (y/n) "); 
If (getchar ()=='n') 
{
break; 
} 
} 
} 



/* by name query */

Void Student_Select () 
{
While (1) 
{
Char name [20]. 
Int index; 
Printf (" please enter the names of the students to query: "); 
The scanf (" % s ", & amp; Name); 
getchar(); 
The index=Student_SearchByName (name); 
If (index==1) 
{
Printf (" the student does not exist! \n"); 
} 
The else 
{
Printf (" do you want to query student information for: \ n "); 
Student_DisplaySingle (index); 
} 
Printf (" whether to continue? (y/n) "); 
If (getchar ()=='n') 
{
break; 
} 
} 
} 



/* sort by average */
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