ช่วยดูโค้ดให้หน่อยครับมัน error ไม่รู้จะแก้ยังไงดี

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include <stdio.h>
#include <math.h>
#include <iostream>
#include <cctype>

int endselect()
{
printf("Prease any key to back to main menu.\r\n");
getch();
return 0;
}

int select1()
{
system("cls");
int number;
int i;
printf("Enter number : ");
scanf("%d", &number);

for(i = 1; i<=12;i++){
printf("%d x %d = %d\n", number, i, number*i);
}

return 0;
}
int select2()
{
system("cls");
int salary ;
float vat,allpay ;

printf("Enter yr salary:");
scanf("%d",&salary);
if (salary<5000)
{
vat=0;
}
else if (salary>=5000 && salary<=9999)
{
vat=salary*0.05;
}
else if (salary>=10000 && salary<=19999)
{
vat=salary*0.07;
}
else if (salary>20000)
{
vat=salary*0.10;
}
printf(" Vat = %.1f Bath\n",vat);
allpay = salary+vat;
printf(" AllPay = %.1f Bath\n",allpay);

return 0;
}

int select3()
{
system("cls");
using namespace std;

void getColorCode(char colorCode[]);
long getResistorValue(char colorCode[]);

char colorCode[3];

void main (int) { <<<<< [บรรทัดที่ 71 error]
long r_value = 0;
printf("This program will calculate the value of a resistor.\n\n");
printf("B = Black\nN = Brown\nR= Red\nO = Orange\nY = Yellow\n");
printf("G = Green\nL = Blue\nV = Violet\nE = Gray\nW = White\n\n");
printf("Enter the 4-character color description of the resistor: ");
getColorCode(colorCode);

r_value = getResistorValue(colorCode);
printf("\n\nThe resistor with color code %c %c %c has a value of %d Ohms.\n", colorCode[0], colorCode[1], colorCode[2], r_value);
return 0;
}

void getColorCode(char colorCode[]) {
int i;
for(i = 0; i < 4; i++)
colorCode[i] = getchar();
}

long getResistorValue( char colorCode[] ) {

int i;
double multiplier;
char band_color;
long value;
int colorValue[3];

for(i = 0; i < 3; i++) {
band_color = toupper(colorCode[i]);
switch (band_color) {
case('B'):
colorValue[i] = 0;
break;
case('N'):
colorValue[i] = 1;
break;
case('R'):
colorValue[i] = 2;
break;
case('O'):
colorValue[i] = 3;
break;
case('Y'):
colorValue[i] = 4;
break;
case('G'):
colorValue[i] = 5;
break;
case('L'):
colorValue[i] = 6;
break;
case('V'):
colorValue[i] = 7;
break;
case('E'):
colorValue[i] = 8;
break;
case('W'):
colorValue[i] = 9;
break;
default:
printf("\nERROR: Color Code %c is not a valid choice\n", colorCode[i]);
break;
}
}
multiplier = pow( 10, (double) colorValue[2]);
value = (((colorValue[0]*10) + colorValue[1]) * multiplier);
return value;
}





int menu()




return 0;
} <<<<<<[แจ้งเตือนบรรทัดนี้]

int main()
{ <<<<<<[บรรทัดmuj 154 error]
char quit;
int select,chk;
while(quit != 'y')
{
system("CLS");
printf("#############################\r\n");
printf("### Menu ###\r\n");
printf("1. Sudkoon\r\n");
printf("2. Calculate Tax\r\n");
printf("3. Calculate Resistor\r\n");
printf("Or other key to exit program\r\n");
printf("Select number(1-3) : ");
select = getch();
printf("\r\n");
chk = 0;
if(select == '1')
{
chk = select1();
}
if(select == '2')
{
chk = select2();
}
if(select == '3')
{
chk = select3();
}



if(chk == 0)
{
printf("Do you want to exit program ? (y or n) : ");
quit = getch();
}
}
return 0;
}

มันerror 2 จุดอะครับ บรรทัดที่ 71 แล้วก็ บรรทัดที่ 154

บรรทัดที่ 71 error แบบนี้ครับ
71: Declaration syntax error in function select3()
บรรทัดที่ 154
154: Cannot overload 'main'
บรรทัดที่ 151 ขึ้นแจ้งเตือน
151: Function should return a value in function select3()