Nested functions! error. please Enlighten me - c

Question

Guys can you help me solve this problem is c programming. I dont get it why i get nested functions when i try to compile the code. I always got ISO forbids nested functions. Please help me understand the code. 3 days. im loosing my mind. Im still new to c programming. thank you!
#include<stdio.h>
#define lcost 35;
#define tax 0.85;
void readData(int* Len,int* Wid,float* Disc,float* cost);
int calcInPrice(float area,float iPrice,float cost,int Len,int Wid);
int calcSTotal(float sTotal,float Disc,float iPrice,float tDisc);
int calcTPrice(float tPrice,float ctax,float sTotal);
void printMes(int Len, int Wid);
void printCharges(float area,float cost,float iPrice,float Disc,float tDisc,float tPrice,float ctax,float sTotal);
int main(void)
{
int x;
int Len, Wid;
float item;
float area, cost, Disc, iPrice, sTotal, tDisc, tPrice, ctax;
do{
system("cls");
printf("[1] Perform\n");
printf("[2] Exit progres\n");
printf("\n\nInput Selection:");
scanf("%d", &x);
switch (x)
{
case 1:
readData(&Len,&Wid,&Disc,&cost);
calcInPrice(area,iPrice,cost,Len,Wid);
calcSTotal(sTotal,Disc,iPrice,tDisc);
printMes(Len,Wid);
printCharges(area,cost,iPrice,Disc,tDisc,sTotal,ctax,tPrice);
printf("\n\nPress any key to return to main menu");
getch();
break;
case2:
system("cls");
printf("Exiting Program");
break;
default:
printf("\n\nInvalid Selection!");
}
}while(x < 3);
void readData(int* Len,int* Wid,float* Disc,float* cost)
{
printf("Input Length of Room: ");
scanf("%d",Len);
printf("Input Width of Room: ");
scanf("%d",Wid);
printf("Input Discount of Customer: ");
scanf("%f",Disc);
printf("Input the cost per square foot: ");
scanf("%f",cost);
return;
}
int calcInPrice(float area,float iPrice,float cost,int Len,int Wid)
{
area = Len * Wid;
iPrice = (lcost * area) + (cost * area);
return;
}
int calcSTotal(float sTotal,float Disc,float iPrice,float tDisc)
{
Disc = (Disc / 100)*iPrice;
sTotal = iPrice - (tDisc);
return;
}
int calcTPrice(float tPrice,float ctax, float sTotal)
{
ctax = sTotal * tax;
tPrice = sTotal + ctax ;
}
void printMes(int Len, int Wid)
{
printf("\n\t\tMEASUREMENT\n\n");
printf("Length\t\t %d ft", Len);
printf("Width\t\t %d ft", Wid);
printf("\nArea\t\t %d square ft", Len * Wid);
return;
}
void printCharges(float area,float cost,float iPrice,float Disc,float tDisc,float tPrice,float ctax,float stotal)
{
float item = cost * area;
printf("\n\n\t\tCHARGES\n\n");
printf("DESCRIPTION\tCOST/SQ.FT.\tCHARGE");
printf("\n________\t _________\t______");
printf("\nCarpet \t%.2f \t %0.2f ",cost,item);
printf("\nLabor \t %lf \t %0.2f",lcost, area);
printf("\n\t\t\t__________");
printf("INSTALLED PRICE \t\t %.2f", iPrice);
printf("\nDiscount \t %.2f \t %.2f ",Disc,tDisc);
printf("\n\t\t\t\t______");
printf("\nSUBTOTAL\t\t\t %.2f",sTotal);
printf("\nTax\t\t\t\t %2f",ctax);
printf("\nTOTAL\t\t\t\t %.2f",tPrice);
return;
}
return 0;
}

Answer 1

Your code looks like this:
int main(void)
{
...
void readData(int* Len,int* Wid,float* Disc,float* cost)
{
...
}
... more functions ...
void printCharges(float area,float cost,float iPrice,float Disc,float tDisc,float tPrice,float ctax,float stotal)
{
...
}
return 0;
}
which means that you're "nesting" all of your function definitions (readData, printCharges, etc.) inside your main function.
That's not allowed.
Instead, you need to write something more like this:
int main(void)
{
...
return 0;
}
void readData(int* Len,int* Wid,float* Disc,float* cost)
{
...
}
... more functions ...
void printCharges(float area,float cost,float iPrice,float Disc,float tDisc,float tPrice,float ctax,float stotal)
{
...
}

Answer 2

You cannot define a function within another function in standard C.
You can declare a function inside of a function, but it's not a nested function.
gcc has a language extension that allows nested functions. They are nonstandard, and as such are entirely compiler-dependent.

Answer 3

The problem is that your main function doesn't end before you start to define your readData() function, so to the compiler it looks like you are defining "readData()" inside of main(). This is called nesting, and is not valid in C. This is one reason why it's important to choose a style for indentation and bracket placement in languages like C.
I'm going to help you figure out how to figure out how to fix it, by winding your program back to a better basis to start from, and you can gradually reintroduce the rest of your code -- don't just add it all in at once, but add it piece-by-piece and make sure it works as you go.
#include <stdio.h>
// proto-type, tells the compiler that we will define this function later.
void readData(int*, int*, float*, float*);
int main()
{
int Len, Wid;
float Disc, Cost;
printf("in main\n");
readData(&Len, &Wid, &Disc, &Cost);
return 0;
} // end of main()
void readData(int* Len, int* Wid, float* Disc, float* Cost)
{
printf("We're in readData now\n");
} // end of readData()
Here it is on ideone so you can see it works.