c语言基础练习题求解

#include
void shan(char a[80],char b[80])
{
        int i,j;
        j=0;
        for(i=0;a[i]!='\0';i++)
                if((a[i]<'0')||a[i]>'9')
                {
                        b[j]=a[i];
                        j++;
                }
        b[j]='\0';
}
void main()
{
        char a[80],b[80];
        int i,c;
        gets(a);
        c=0;

        for(i=0;a[i]!='\0';i++)
        {
                if(((a[i]>='a')&&(a[i]<='z'))||((a[i]>='A')&&(a[i]<='Z')))
                        c++;
        }

        if(c==0)
                printf("ERROR\n");
        else
        {
                shan(a,b);
                puts(b);
        }
}