Turbo C 2.0: Complete 2000-Word Guide to Installation, Configuration, Errors, I/O, Graphic

Turbo C 2.0 is one of the classic and most influential C compilers used by programmers, students, and developers during the DOS era. Even today, many academic institutions still teach C programming using Turbo C because of its simple Integrated Development Environment (IDE) and easy-to-use tools. Although modern compilers are far more advanced, Turbo C remains an important learning tool for understanding the foundations of C programming.

This comprehensive guide answers the most common questions related to Turbo C 2.0—installation, configuration, compiler usage, linker errors, graphics handling, file I/O, memory issues, and more. Whether you are a beginner trying Turbo C for the first time or a student preparing for lab exams, this detailed blog post will help you solve every typical issue encountered.

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1. Installing Turbo C 2.0

Before writing programs, Turbo C must be properly installed. The installation process is straightforward and uses an INSTALL program stored on the installation disk.

How to Install Turbo C

To begin installation:

1. Insert the Turbo C disk (INSTALL/HELP disk).

2. Change your active drive to the installation disk by typing:

   A:
   

3. Run the INSTALL program:

   INSTALL
   

4. Follow the on-screen menu prompts to choose:

   • Destination directory

   • Source drive

   • Installation options

Turbo C will automatically copy files, set up directories, and generate configuration files needed for both the Integrated Environment (TC.EXE) and command-line compiler (TCC.EXE).

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2. Running Turbo C

Once installed successfully, running Turbo C is simple. From the DOS prompt, type:

TC

This starts the Integrated Development Environment (IDE) which includes:

• Built-in editor

• Compiler

• Linker

• Debugger.

Users can start writing code immediately, compile it, and test it inside the same environment.

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3. Difference Between TC.EXE and TCC.EXE

Turbo C comes with two compilers, each designed for different purposes:

1. TC.EXE (Integrated Environment)

• Full-screen editor

• Built-in debugger

• Integrated compiler and linker

• Menu-driven interface

2. TCC.EXE (Command-line Compiler)

• Faster, lightweight

• Suitable for batch operations

• No GUI

• Requires manual use of makefiles, library paths, and switches

Both compilers use the same backend but differ in how users interact with them.

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4. Configuration Files in Turbo C

Turbo C depends on configuration files to locate libraries, header files, and set default options.

Types of Configuration Files

• TC.EXE uses: TCCONFIG.TC

• TCC.EXE uses: TURBOC.CFG

When INSTALL runs, it automatically creates TURBOC.CFG but embeds directory information directly into TC.EXE, so TCCONFIG.TC must be created manually.

Creating Configuration Files

For TC.EXE, run the IDE → adjust settings → press Alt + O + S to save options.

For TCC.EXE, edit the ASCII file TURBOC.CFG manually.

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5. Integrated Environment (IDE) – Common Questions

Why Turbo C Can’t Find Header Files (#include)?

Header file search paths are defined under:

Options → Directories → Include Directories

If incorrect, update the path where .h files are located.

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“Unable to open input file 'C0x.OBJ'” – Why?

The linker cannot locate startup and library files.
Fix it by updating:

Options → Directories → Library Directories

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How to Use Multiple Source Files or Custom Libraries?

Turbo C includes a Project Manager that lets users group multiple .C files and link external libraries.

Use:

Project → Open Project

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Graphics Library Functions Undefined

If using graphics, enable:

Options → Linker → Graphics Library → ON

or include GRAPHICS.LIB in your project file.

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Why “Unable to open include file 'stdarg.h'”?

DOS has a limit on simultaneous open files.
Edit CONFIG.SYS and add:

FILES=20

Reboot the system afterward.

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How to Change Colors in Turbo C Editor?

Use the utility:

TCINST.EXE

This allows color customization for menus, windows, and editor background.

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How to Print the Program Code?

Press:

Shift + PrtSc

or use the editor command to print the current file or selected block.

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MAKE Always Rebuilds the Project

If any file has a future date/time stamp, MAKE thinks it is outdated.
Use TOUCH.COM or correct the system clock.

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6. Command-Line Compiler (TCC.EXE)

Include Files Not Found?

Use the -I option:

TCC -Ic:\turboc\include

Startup/Library Files Missing?

Use the -L option:

TCC -Lc:\turboc\lib

Graphics Library Undefined

Manually specify:

TCC BGIDEMO.C GRAPHICS.LIB

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7. General Input/Output (I/O) Questions

Why Does cprintf() Not Move to Start of Line?

In Turbo C, \n is only line feed, not carriage return.

Use:

cprintf("\n\r");

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How to Print to Printer from Turbo C Program?

Use stdprn:

fprintf(stdprn, "Hello printer!\n");

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How to Read and Write Binary Files Correctly?

Always open file in binary mode using "rb" or "wb".

FILE *fp = fopen("data.bin", "rb");

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Why printf() Doesn’t Print Color?

Use console I/O functions:

textcolor(RED);
cprintf("Colored text");

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How to Print Long Integer or Long Double?

printf("%ld", l);
printf("%Lf", ld);

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8. Example Programs & Compilation

Compiling MICROCALC

Refer to Appendix G of the Turbo C Reference Manual.

Compiling BGIDEMO

Steps:

1. Keep .BGI and .CHR files in the same directory.

2. Open BGIDEMO.C inside TC.

3. Press Ctrl + F9 to run.

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9. Creating COM Files

Turbo C usually creates EXE files, but a COM file can be produced using:

tcc -mt -lt tinyfile

Limitations:

• COM files support only Tiny memory model

• Programs using floating point cannot be compiled into COM

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10. Graphics Programming Questions

Why “BGI Error: graphics not initialized”?

initgraph() failed. Check the error:

int err = graphresult();
printf("%s", grapherrormsg(err));

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11. Math & Floating Point Issues

Incorrect Results from cos(), tan() etc.?

Always include the math header:

#include <math.h>

Otherwise, Turbo C assumes the function returns int.

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How to Trap Floating Point Errors?

Use:

• signal() for runtime 8087/Emulator errors

• matherr() for library math errors

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12. Linker Errors and Their Fixes

Undefined Symbol '_main'

Every C program must include:

void main() { }

or

int main() { }

Also ensure the file containing main() is part of the project.

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Undefined Graphics Library Functions

Enable Graphics Library or manually include GRAPHICS.LIB.

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Assembly Functions Undefined

Turbo C uses leading underscore for external symbols.
Assembly functions must be declared as:

_public _myfunc

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13. Memory, Pointer & Stack Issues

Changing Stack Size

Add:

extern unsigned _stklen = 10000;

outside all functions.

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Stack Overflow Solution

Use static for large local arrays:

static char bigarray[5000];

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Null Pointer Assignment Error

Caused by:

• Uninitialized pointers

• Memory corruption

• Overwriting memory

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Why TC.EXE Creates Larger EXE Files?

Because debugging information is embedded by default.
Disable via:

Alt + D → S → N

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Large Model Program Hangs with malloc()

Always include the correct header:

#include <alloc.h>

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Pointer Crossing 64K Boundary

Use huge pointers.

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Declaring Arrays Larger Than 64K

Must allocate from heap:

char (huge *arr)[128];
arr = farcalloc(1024, sizeof(*arr));

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14. Turbo C with Other Languages

Using Assembly with Turbo C

Ensure:

• Case sensitivity ON

• Function names begin with _

• Correct segment declarations

Interfacing Turbo C with Turbo Pascal

Use:

• CPASDEMO.PAS

• CPASDEMO.C

Both included in EXAMPLES.ARC.

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15. Turbo C and Clipper

Some versions may cause linking issues.
Developers should contact Nantucket Technical Support for Clipper-specific guidance.

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Conclusion

Turbo C 2.0 remains a fundamental tool for understanding classic C programming, memory models, pointers, graphics, compiler behavior, and DOS-based application development. Despite being replaced by modern compilers, Turbo C teaches valuable low-level concepts that help students grasp how C works under the hood.

This guide provides solutions to every common Turbo C problem, making it easier to install, configure, compile, debug, and run C programs efficiently. Whether you're learning C for academics or exploring retro programming environments, Turbo C continues to serve as an excellent starting point.