C :

int main(int argc, char* argv[])
{int n,len,i;
char s[81];
scanf("%d%*c",&n);
while(n--)
{
gets(s);
len=strlen(s);
for(i=0;i<len;i++)
{
if('a'<=s[i]&&s[i]<='y')s[i]+=1; 
else if('z'==s[i])s[i]='a';
if('A'<=s[i]&&s[i]<='Y')s[i]+=1;
else if('Z'==s[i])s[i]='A';
}
puts(s);
}
	return 0;
}

Python :

# coding=utf-8
x = int(input())
for a in range(0,x):
    y =str(input())
    s = ''
    for i in y:
        if 'a' <= i <= 'y' or 'A' <= i <= 'Y':
            s += chr(ord(i)+1)
        elif i ==  'z':
            s += 'a'
        elif  i == 'Z':
            s += 'A'
        else:
            s += i
    print(s)