Go: package main

import (
	"bytes"
	"fmt"
)

//Ktai has a keyboard and a state.
type Ktai struct {
	keyboard KeyBoard
	textBuf  *bytes.Buffer
}

// KeyBoard is type of a map.
type KeyBoard map[rune]string

// KEYBOARD that Ktai has
var KEYBOARD = KeyBoard{
	'0': "",
	'1': ".,!? ",
	'2': "abc",
	'3': "def",
	'4': "ghi",
	'5': "jkl",
	'6': "mno",
	'7': "pqrs",
	'8': "tuv",
	'9': "wxyz",
}

func main() {
	var N int
	fmt.Scanf("%d", &N)
	ktai := &Ktai{
		KEYBOARD, &bytes.Buffer{},
	}
	for i := 0; i < N; i++ {
		var numstr string
		fmt.Scanf("%s", &numstr)
		ktai.feed(numstr)
		ktai.print()
	}
}

func (ktai *Ktai) feed(str string) {
	var char *byte
	for _, v := range str {
		if v == '0' {
			if char != nil {
				ktai.textBuf.WriteByte(*char)
				char = nil
			}
			continue
		} else {
			runestring := ktai.keyboard[v]
			idx := ktai.indexOf(char, runestring)
			next := (idx + 1) % len(runestring)
			c := runestring[next]
			char = &c
		}
	}
}

func (ktai *Ktai) indexOf(ch *byte, str string) int {
	if ch == nil {
		return -1
	}
	r := rune(*ch)
	idx := -1
	for i, v := range str {
		if r == v {
			idx = i
			break
		}
	}
	return idx
}

func (ktai *Ktai) print() {
	fmt.Println(ktai.textBuf.String())
	ktai.textBuf.Reset()
}

C++: #include <algorithm>
#include <cctype>
#include <cstdio>
#include <iostream>
#include <locale>
#include <numeric>
#include <string>
#include <vector>

using namespace std;

string solve(string s){
    int count=0;
    string ans;
    char keep;
    string keeps;
    char c;
    for(int i=0;i<s.size();i++){
        // char k=s[i];
        if(s[i]!='0'){
            count++;
            c=s[i];
        }
        else{
                if(c== '2'){
                    if(count%3==1)ans.append(1,'a');
                    else if(count%3==2)ans.append(1,'b');
                    else ans.append(1,'c');
                }
                else if(c== '3'){
                    if(count%3==1)ans.append(1,'d');
                    else if(count%3==2)ans.append(1,'e');
                    else ans.append(1,'f');
                }
                else if(c== '4'){
                    if(count%3==1)ans.append(1,'g');
                    else if(count%3==2)ans.append(1,'h');
                    else ans.append(1,'i');
                }
                else if(c== '5'){
                    if(count%3==1)ans.append(1,'j');
                    else if(count%3==2)ans.append(1,'k');
                    else ans.append(1,'l');
                }
                else if(c== '6'){
                    if(count%3==1)ans.append(1,'m');
                    else if(count%3==2)ans.append(1,'n');
                    else ans.append(1,'o');
                }
                else if(c== '7'){
                    if(count%4==1)ans.append(1,'p');
                    else if(count%4==2)ans.append(1,'q');
                    else if(count%4==3)ans.append(1,'r');
                    else ans.append(1,'s');
                }
                else if(c== '8'){
                    if(count%3==1)ans.append(1,'t');
                    else if(count%3==2)ans.append(1,'u');
                    else ans.append(1,'v');
                }
                else if(c== '9'){
                    if(count%4==1)ans.append(1,'w');
                    else if(count%4==2)ans.append(1,'x');
                    else if(count%4==3)ans.append(1,'y');
                    else ans.append(1,'z');
                }
                else if(c== '1'){
                    if(count%4==1)ans.append(1,'.');
                    else if(count%4==2)ans.append(1,',');
                    else if(count%4==3)ans.append(1,'!');
                    else ans.append(1,'?');
                }
            count=0;
        }
    }
    // cout << ans << "%%%%%%%%%%%%%%%%"<<endl;
    return ans;
}

int main(int argc, char const *argv[]) {
    cin.tie(0);
    int n;
    cin >> n;
    string s;
    vector<string>ans;
    for(int i=0;i<n;i++){
        cin >> s;
        ans.push_back(solve(s));
    }
    for(int i=0;i<n;i++){
        cout << ans[i]<<endl;
    }
}