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 <iostream>
#include <string>
using std::cin;
using std::cout;
using std::endl;
using std::string;

int main(){
  string kigo = ".,!? ";
  string a = "abc";
  string d = "def";
  string g = "ghi";
  string j = "jkl";
  string m = "mno";
  string p = "pqrs";
  string t = "tuv";
  string w = "wxyz";
  string syu;
  int keta,n,count;
  int flag1 = 0;
  int flag2 = 0;
  cin >> n;
  string nn;
  for(int i = 0; i < n;i++){
    cin >> nn;
    syu = "";
    for(int i = 0; i < nn.length();i++){
      if(nn[i] == '1'){
        flag1 = 1;
        flag2 += 1;
      }else if(nn[i] == '2'){
        flag1 = 2;
        flag2 += 1;
      }else if(nn[i] == '3'){
        flag1 = 3;
        flag2 += 1;
      }else if(nn[i] == '4' ){
        flag1 = 4;
        flag2 += 1;
      }else if(nn[i] == '5'){
        flag1 = 5;
        flag2 += 1;
      }else if(nn[i]== '6'){
        flag1 = 6;
        flag2 += 1;
      }else if(nn[i] == '7'){
        flag1 = 7;
        flag2 += 1;
      }else if(nn[i] == '8'){
        flag1 = 8;
        flag2 += 1;
      }else if(nn[i] == '9'){
        flag1 = 9;
        flag2 += 1;
      }else if(nn[i] == '0'){
        if(flag1 == 0){
        }else{
          flag2 -= 1;
          if(flag1 == 1){
            syu += kigo[(flag2)%5];
            flag1 = 0;
          }else if(flag1 == 2){
            syu += a[flag2%3];
            flag1 = 0;
          }else if(flag1 == 3){
            syu += d[flag2%3];
            flag1 = 0;
          }else if(flag1 == 4){
            syu += g[flag2%3];
            flag1 = 0;
          }else if(flag1 == 5){
            syu += j[flag2%3];
            flag1 = 0;
          }else if(flag1 == 6){
            syu += m[flag2%3];
            flag1 = 0;
          }else if(flag1 == 7){
            syu += p[flag2%4];
            flag1 = 0;
          }else if(flag1 == 8){
            syu += t[flag2%3];
            flag1 = 0;
          }else if(flag1 == 9){
            syu += w[flag2%4];
            flag1 = 0;
          }
          flag2 = 0;
        }
      }
    }
      cout << syu << endl;
  }
}

C++: #include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<vector>

using namespace std;

int main(void){
  string a[10];

  a[0]="";
  a[1]=" .,!?";
  a[2]="cab";
  a[3]="fde";
  a[4]="igh";
  a[5]="ljk";
  a[6]="omn";
  a[7]="spqr";
  a[8]="vtu";
  a[9]="zwxy";

  int n;
  cin >> n;
  cin.ignore();
  while(n--){
    string str;
    getline(cin,str);

    int sz=str.size(),i=0,cnt=0;
    while(str[i]=='0')i++;
    for(;i<sz;i++){
      if(str[i]=='0'){
	cout << a[str[i-1]-'0'][cnt%a[str[i-1]-'0'].size()];
	cnt=0;
	while(str[i+1]=='0')i++;
      }
      else cnt++;
    }
    cout << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <algorithm>
using namespace std;
string tbl[]={"",".,!? ","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};

int main(){
  int t;
  cin>>t;
  while(t--){
    string s;
    cin>>s;
    int p=0,c=0;
    for(int i=0;i<s.length();++i){
      if(s[i]=='0'){
	if(p||c) cout<<tbl[p][c%tbl[p].length()];
	p=0;
	c=0;
      }
      else{
	if(!p) p=s[i]-'0';
	else ++c;
      }
    }
    cout << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <time.h>
#include <math.h>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <iterator>
#include <sstream>
#include <string>
#include <bitset>
using namespace std;
#define FOR(I,F,N) for(int I = F; I < (int)(N); I++)
#define rep(i, n) FOR(i, 0, n)
#define FIN(V) cout<<V<<endl
#define pb push_back
#define INF (1 << 28)

template<typename T>
void remove(vector<T>& vector, unsigned int index){
vector.erase(vector.begin() + index);
}

typedef pair<int, int> P;
typedef long long ll;
typedef priority_queue<int> pq;
int StrToInt(string);
string IntToStr(int);
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};

string s[] = {"",".,!? ", "abc", "def", "ghi", "jkl", "mno", "pqls", "tuv", "wxyz"};

int main(void){
	int n;
	cin >> n;
	rep(k,n){
		string L;
		cin >> L;
		int count = 0;
		for(int i = 0; i < L.size(); i++){
			if(L[i] == '0'){
				if(count == 0)continue;
				int type = L[i-1]-'0';
				if(L[i] != '0')cout << s[type][(count-1)%s[type].size()];
				count = 0;
				continue;
			}
		}
		cout << endl;
	}
	return 0;
}



int StrToInt(string s){
	stringstream ss;
	ss << s;
	int val;
	ss >> val;
	return val;
}
string IntToStr(int i){
	stringstream ss;
	ss << i;
	return ss.str();
}

C++: #include <iostream>
#include <string>

using namespace std;

int main()
{
    string messages[9]= {".,!? ", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
    int n;
    cin >> n;

    for (int i = 0; i < n; i++) {
        string msg;
        // string output = "";
        int count = 0;
        char prev = '0';

        cin >> msg;

        for (int j = 0; j < (int)msg.size(); j++) {
            char c = msg[j];

            if (c == '0' && j != 0) {
                if (prev == '1') {
                    cout << messages[0][(count-1) % 5];
                } else if (prev == '2') {
                    cout << messages[1][(count-1) % 3];
                } else if (prev == '3') {
                    cout << messages[2][(count-1) % 3];
                } else if (prev == '4') {
                    cout << messages[3][(count-1) % 3];
                } else if (prev == '5') {
                    cout << messages[4][(count-1) % 3];
                } else if (prev == '6') {
                    cout << messages[5][(count-1) % 3];
                } else if (prev == '7') {
                    cout << messages[6][(count-1) % 4];
                } else if (prev == '8') {
                    cout << messages[7][(count-1) % 3];
                } else if (prev == '9') {
                    cout << messages[8][(count-1) % 4];
                }
                count = 0;
            } else {
                count++;
            }
            prev = msg[j];
        }
        cout << endl;
    }

    return 0;
}