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++: #define	_USE_MATH_DEFINES
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cfloat>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <string>
#include <set>
#include <complex>
#include <utility>
#include <numeric>
#define  rep(i,n) for(int i=0;i<(n);i++)
#define  REP(i,a,n) for(int i=a;i<(n);i++)
#define  rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define  VI	vector<int>
#define	 VS vector<string>
#define  all(a) (a).begin(),(a).end()
#define  debug(x) cout<<#x<<": "<<x<<endl
using namespace std;
typedef pair<int,int> P;
typedef long long ll;

const int INF=1000000;
char fi[101][101];
int d[21][21];
int day[12]={31,28,31,30,31,30,31,31,30,31,30,31};
int N,M;
int sx,sy;
int gx,gy;
int w,h;
int ans;

int dx[4]={0,0,-1,1};
int dy[4]={-1,1,0,0};
const int MAX_V=100;
const int MAX_N=100;
char o[3]={'+','-','*'};
#define md 1000003

int dp[353][353]={0};
int bow[353][353]={0};


int main(){
	
	string s;
	
	while(cin>>s){
		vector<string> p(10);
		p[1]=".,!? ";
		p[2]="abc";
		p[3]="def";
		p[4]="ghi";
		p[5]="jkl";
		p[6]="mno";
		p[7]="pqrs";
		p[8]="tuv";
		p[9]="wxyz";
		bool f=false;
		char c='0';
		int count=0;
		string a="";
		rep(i,s.size()){
			if(s[i]=='0'){
				if(f){
				if(c=='1'){
					count=(count-1)%5;
				}
				else if(c=='7'||c=='9'){
					count=(count-1)%4;
				}
				else{
					count=(count-1)%3;
				}
				a+=p[c-'0'][count];
				f=false;
				count=0;
				c='0';
				}
			}
			else{
				f=true;
				if(c!=s[i]){
					c=s[i];
					count=1;
				}
				else
					count++;
				
			}
			
		}
		if(a!="")
		cout<<a<<endl;
	}
	
}

C++: #include <bits/stdc++.h>
using namespace std;
#define int long long
#define Rep(i, N) for(int i = 0; i < N; i++)
#define Reps(i, x, N) for(int i = x; i < N; i++)

const int LLINF = 1LL << 60;

string pat[9] = {".,!? ", "abc", "def", "ghi", "jkl", "mno", "pqrs" , "tuv" , "wxyz"};

signed main()
{
  int N;
  
  cin >> N;
  while(N--) {
    string S, T;
    cin >> S;
    
    int i = 0;
    while(i < S.size()) {
      int cnt = -1, choice = -1;
      while(i < S.size() && S[i] != '0') {
	cnt++; choice = S[i] - '1'; i++;
      }
      if(~choice) {
	T += pat[choice][cnt % pat[choice].size()];
      }
      i++;
    }

    cout << T << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>

int main(void)
{
  int n;
  char buf[1025];
  int count=0;
  int tmp;

  scanf("%d",&n);
  for(int i=0;i<n;i++){
    scanf("%s",buf);
    for(int j=0;buf[j]!='\0';j++){
      if(buf[j]=='\n')continue;
      
      if(buf[j]!='0'){
	tmp = buf[j]-'0';
	count++;
      }
      else{
	if(count==0){continue;}
	switch(tmp){
	case 1:
	  if(count%4==1)printf(" ");
	  if(count%4==2)printf(",");
	  if(count%4==3)printf("!");
	  if(count%4==0)printf("?");
	  break;
	case 2:
	  if(count%3==1)printf("a");
	  if(count%3==2)printf("b");
	  if(count%3==0)printf("c");
	  break;
	case 3:
	  if(count%3==1)printf("d");
	  if(count%3==2)printf("e");
	  if(count%3==0)printf("f");
	  break;
	case 4:
	  if(count%3==1)printf("g");
	  if(count%3==2)printf("h");
	  if(count%3==0)printf("i");
	  break;
	case 5:
	  if(count%3==1)printf("j");
	  if(count%3==2)printf("k");
	  if(count%3==0)printf("l");
	  break;
	case 6:
	  if(count%3==1)printf("m");
	  if(count%3==2)printf("n");
	  if(count%3==0)printf("o");
	  break;
	case 7:
	  if(count%4==1)printf("p");
	  if(count%4==2)printf("q");
	  if(count%4==3)printf("r");
	  if(count%4==0)printf("s");
	  break;
	case 8:
	  if(count%3==1)printf("t");
	  if(count%3==2)printf("u");
	  if(count%3==0)printf("v");
	  break;
	case 9:
	  if(count%4==1)printf("w");
	  if(count%4==2)printf("x");
	  if(count%4==3)printf("y");
	  if(count%4==0)printf("z");
	  break;
	}
	count=0;
      }
    }
    printf("\n");
  }
      
  return 0;
}

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

#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;
string keys[10];
string input;

void solve() {
    string ans;
    string now;
    int cnt = 0;
    for (auto c : input) {
        if (c == '0') {
            ans += now;
            now = "";
            cnt = 0;
        } else {
            now = keys[c - '0'][cnt];
            cnt++;
            cnt %= keys[c - '0'].size();
        }
    }
    cout << ans << endl;
}

int main() {
    keys[1] = ".,!? ";
    keys[2] = "abc";
    keys[3] = "def";
    keys[4] = "ghi";
    keys[5] = "jkl";
    keys[6] = "mno";
    keys[7] = "pqrs";
    keys[8] = "tuv";
    keys[9] = "wxyz";
    int n;
    cin >> n;
    rep(i, n) {
        cin >> input;
        solve();
    }
}

C++: #include <iostream>
#include <string>
using namespace std;

#define Rep(i,n) for(int i=0;i<n;i++)
#define rep(i,a,b) for(int i=a;i<b;i++)

void b(int a,int count);

int main(){
  int n;
  cin >> n;
  Rep(i,n){
    string s;
    cin >> s;

    int d=1;
    string pre = s.substr(0,1);
    rep(j,1,s.size()){
      if(pre == s.substr(j,1) ) d++;
      else{
	int num = stoi(pre);
	b(num,d);
	pre = s.substr(j,1);
	d=1; 
      }
    }
    cout << endl;
  }
}

void b(int a,int count){
  if(a == 1){
    if(count%5==1) cout <<".";
    else if(count%5==2) cout <<",";
    else if(count%5==3) cout <<"!";
    else if(count%5==4) cout <<"?";
    else if(count%5==0) cout <<" ";

  }
  else if(a == 2){
    if(count%3==1) cout <<"a";
    else if(count%3==2) cout <<"b";
    else if(count%3==0) cout <<"c";
  }
  else if(a == 3){
    if(count%3==1) cout <<"d";
    else if(count%3==2) cout <<"e";
    else if(count%3==0) cout <<"f";
  }
  else if(a == 4){
    if(count%3==1) cout <<"g";
    else if(count%3==2) cout <<"h";
    else if(count%3==0) cout <<"i";
  }
  else if(a == 5){
    if(count%3==1) cout <<"j";
    else if(count%3==2) cout <<"k";
    else if(count%3==0) cout <<"l";
  }
  else if(a == 6){
    if(count%3==1) cout <<"m";
    else if(count%3==2) cout <<"n";
    else if(count%3==0) cout <<"o";
  }
  else if(a == 7){
    if(count%4==1) cout <<"p";
    else if(count%4==2) cout <<"q";
    else if(count%4==3) cout <<"r";
    else if(count%4==0) cout <<"s";
  }
  else if(a == 8){
    if(count%3==1) cout <<"t";
    else if(count%3==2) cout <<"u";
    else if(count%3==0) cout <<"v";
  }
  else if(a == 9){
    if(count%4==1) cout <<"w";
    else if(count%4==2) cout <<"x";
    else if(count%4==3) cout <<"y";
    else if(count%4==0) cout <<"z";
  }
  return;
}