想请问一下为什么运行正常，代码提交就显示好多问题，百度完也没怎么看明白

#include <stdio.h>
#include <string.h>
int main()
{
    int i,n,m,j,k=0,e,t=0;
    char a[11]={'\0'},b[1000001]={'\0'};
    gets(a);
    gets(b);
    strupr(a);
    strupr(b);
    strcat(a," ");
    strcat(b," ");
    m=strlen(a);
    n=strlen(b);
    for(i=0;b[i]!='\0';i++)
    {
        if(i==0||b[i-1]==' ')
            for(j=0;j<m;j++)
        {
            if(b[i+j]!=a[j])
                break;
        }
        if(j==m)
        {
            t=1;
            e=i;
            break;
        }

    }
    if(b[i]=='\0')
        t=0;
        if(t==1)
{
    for(i=0;i<n;i++)
    {
         if(i==0||b[i-1]==' ')
        for(j=0;j<m;j++)
        {
            if(b[i+j]!=a[j])
                break;
        }
        if(j==m)
        {
            k++;
            i+=m-1;
        }
    }
     printf("%d %d",k,e);
}
  if(t==0)
    printf("-1");
    return 0;
}

/tmp/compiler_06p4qay4/src: 在函数‘int main()’中: /tmp/compiler_06p4qay4/src:7:5: 错误：‘gets’ was not declared in this scope; did you mean ‘fgets’? 7 | gets(a); | ^~~~ | fgets /tmp/compiler_06p4qay4/src:9:5: 错误：‘strupr’ was not declared in this scope; did you mean ‘strstr’? 9 | strupr(a); | ^~~~~~ | strstr /tmp/compiler_06p4qay4/src:31:5: 警告：this ‘if’ clause does not guard... [-Wmisleading-indentation] 31 | if(b[i]=='\0') | ^~ /tmp/compiler_06p4qay4/src:33:9: 附注：...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’ 33 | if(t==1) | ^~ /tmp/compiler_06p4qay4/src:51:3: 警告：this ‘if’ clause does not guard... [-Wmisleading-indentation] 51 | if(t==0) | ^~ /tmp/compiler_06p4qay4/src:53:5: 附注：...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’ 53 | return 0; | ^~~~~~