c语言编程问题，我写出代码来了，但是不对，求解，谢谢

#include
int main()
{
    char a[100];
    gets(a);
    int i;
    for(i=0;i<20;i++){
        if(a[i]>='a'&&a[i]<='c')
        a[i]='2';
        else if(a[i]>='d'&&a[i]<='f')
        a[i]='3';
        else if(a[i]>='g'&&a[i]<='i')
        a[i]='4';
        else if(a[i]>='j'&&a[i]<='l')
        a[i]='5';
        else if(a[i]>='m'&&a[i]<='o')
        a[i]='6';
        else if(a[i]>='p'&&a[i]<='s')
        a[i]='7';
        else if(a[i]>='t'&&a[i]<='v')
        a[i]='8';
        else if(a[i]>='w'&&a[i]<='z')
        a[i]='9';
        else if(a[i]>='A'&&a[i]<'Z')
        a[i]=a[i]+32+1;
        else if(a[i]=='Z')
        a[i]='a';
        else a[i]=a[i];
    }

    puts(a);

return 0;}

错的都帮你改好了，你看看把

对了，程序已经转换成功了

#include
int main()
{
int i;
char a[100];
gets(a);
for(i=0;i<20;i++)
if(a[i]>='a'&&a[i]<='c')
a[i]='2';
else if(a[i]>='d'&&a[i]<='f')
a[i]='3';
else if(a[i]>='g'&&a[i]<='i')
a[i]='4';
else if(a[i]>='j'&&a[i]<='l')
a[i]='5';
else if(a[i]>='m'&&a[i]<='o')
a[i]='6';
else if(a[i]>='p'&&a[i]<='s')
a[i]='7';
else if(a[i]>='t'&&a[i]<='v')
a[i]='8';
else if(a[i]>='w'&&a[i]<='z')
a[i]='9';
else if(a[i]>='A'&&a[i]<='Z')
{
a[i]+=33;
a[i]='a'+(a[i]-'a')%26;
}
else
a[i]=a[i];
puts(a);
return 0;
}