[填空题]下列给定程序中函数fun的功能是：统计substr所指的字符串在str所指的字符串中出现的次数。
例如，若字符串为aaas 1kaaas，子字符串为as，则应输出2。
请改正程序中的错误，使它能得出正确的结果。
注意：不要改动main函数，不得增行或删行，也不得更改程序的结构!
试题程序：
#include＜stdio．h＞
int fun(char*str，char*substr)
int i，j，k，num=0；
/*********found*********/
for(i=0，str[i]，i++)
for(j=i，k=0；
substr[k]==str[j]；
k++，j++)
/*********found*********/
If(substr[k+1]==’/0’)
num ++；
break；

return num；

main（　）

char str[80]，substr[80]；
printf("Input a string：")；
gets(str)；
printf("Input a substring：")；
gets(substr)；
printf("%d/n"．fun(str，substr))；

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