c语言向文件输入成绩

Question

{
FILE*fp;
fp=fopen("score_avg.txt","w");
char num,math,engl,cyu;
float avg;
scanf("%d,%d,%d",&math,&engl,&cyu);
num=math+engl+cyu;
avg=num/3;
printf("%d,%.1f",num,avg);
fprintf("%d,%.1f",num,avg);
fclose(fp);
return 0;
}

Answer 1

char num,math,engl,cyu;
改成：
int num,math,engl,cyu;