C语言【输入一些关于学生的数据然后按照学号从小到大排列】

#include<stdio.h>
#include<string.h>
//define a struction.
struct st_basic{
	char name[35];
	int num;
	int scls;
};
//Output is arranged in order of number from small to large.
int main(){
	struct st_basic st[3];
	int i;
	for(i=0;i<3;i++){
		printf("Please input the %d st data:\n",i+1); 
		scanf("%s%d%d",&st[i].name,&st[i].num,&st[i].scls);
	}
	
/*
Here we add a function sorted by student number.
So our program can be sorted according to the number of students.
BUT The range of ints in C language is -2147483648 to 2147483647.
So if the number range exceeds this range, the wrong result will be output.
*/
	int j;
	struct st_basic temp;
	for(i=0;i<2;i++){
		for(j=1;j<=2;j++){
			if(st[i].num>=st[j].num){
				temp=st[i];
				st[i]=st[j];
				st[j]=temp;
			}
		}
	}
//output these data...
	for(i=0;i<3;i++){
		printf("%d>>> %d %s %d\n",i,st[i].num,st[i].name,st[i].scls);
	}
return 0;
}