![Conditional Breakpoints
//file_read.c
input.dat
#include <stdio.h>
#include <string.h> id animal
int main(void) 1 CAT
{ 2 SHEEP
FILE *input_fp = NULL;
char buff[255]; 3 WOLF
int id = 0; 4 DOG
char animal[16];
input_fp = fopen("input.dat","r"); 5 MONKEY
6 EAGLE
while(fgets(buff,sizeof(buff)-1,input_fp) != NULL)
{ 7 MAN
sscanf(buff,"%d %s %*[^n]",&id,animal);
printf("Animal at pos %d is %sn",id,animal);
}
fclose(input_fp);
return 0;
}
How do I stop the
id = 4
execution when](https://image.slidesharecdn.com/cisrodebugging-120217070616-phpapp01/85/C-ISRO-Debugging-19-320.jpg)
![Conditional Breakpoints
//file_read.c
input.dat
#include <stdio.h>
#include <string.h> id animal
int main(void) 1 CAT
{ 2 SHEEP
FILE *input_fp = NULL;
char buff[255]; 3 WOLF
int id = 0; 4 DOG
char animal[16];
input_fp = fopen("input.dat","r"); 5 MONKEY
6 EAGLE
while(fgets(buff,sizeof(buff)-1,input_fp) != NULL)
{ 7 MAN
sscanf(buff,"%d %s %*[^n]",&id,animal);
printf("Animal at pos %d is %sn",id,animal);
}
fclose(input_fp);
return 0;
}
How do I stop the
animal = MAN
execution when](https://image.slidesharecdn.com/cisrodebugging-120217070616-phpapp01/85/C-ISRO-Debugging-21-320.jpg)
C ISRO Debugging
- 1. C a series of presentations to help a bunch of brilliant space scientists understand a brilliant programming language
- 2. Debugging
- 3. Debugging It is the process of finding and removing “bugs” (logical errors) from a program
- 4. bluntly put … … debugging is an art
- 5. depends on … •Skill of programmer •Complexity of the program •Simplicity of the programming language •Availability of debugging tools
- 6. Techniques Print / Trace It involves adding a ‘printf’ statement at various locations to inspect the value stored in the variables Core dump Analysis Analyzing the memory snapshot of the program after the crash. The operating system dumps the entire contents of the memory related to the program into a core dump file. Used to detect memory related bugs in your program. Execution monitoring Step by step execution of the program to analyze the execution path and change in control or data.
- 7. Debugger Debuggers are tools that enable the programmer to monitor the memory and/or execution of the program.
- 8. Demonstration Data Display Debugger (DDD) •DDD is a well known C debugger in the Linux platform. •It’s a GUI based front end for GNU Debugger (gdb) program.
- 9. Demonstration //simple_loop.c 1. Compile the file using #include <stdio.h> the –g flag in gcc int main(void) { int i = 0; $> gcc –g simple_loop.c printf("Entering Loopn"); for(i=0;i<10;i++) { printf("%d ",i); } 2. Load ‘a.out’ in DDD printf("Exiting Loopn"); return 0; $> ddd a.out & } -g flag stores extra information regarding the program which is required for the debugger
- 10. Demonstration Data Window Control Panel Source Code
- 11. Control Panel Start the program Step program until it reaches a different source line Step program, proceeding through subroutine calls Execute until source line reaches greater than current … rest for homework :P
- 12. Breakpoint A breakpoint informs the debugger to freeze execution at a chosen line. A programmer can then evaluate all the variables and stack of the program. Demonstration: setting a breakpoint in DDD
- 13. Breakpoint 1. Right click on the line you wish to set the breakpoint 2. Select ‘Set Breakpoint’
- 14. Conditional Breakpoints A breakpoint that informs the debugger to freeze execution at a chosen line when a desired condition is met . Demonstration: setting a conditional breakpoint in DDD
- 15. Conditional Breakpoint 1. Right click on the new breakpoint 2. Select ‘Properties’
- 16. Conditional Breakpoint 1. Set your required condition in the ‘Condition’ text box 2. Click ‘Apply’
- 17. Conditional Breakpoints //complex_loop.c #include <stdio.h> How do I stop the int main(void) execution when { int i = 0; int j = 0; i = 0 int k = 0; for(i = 0; i < 10; i++) j = 10 { for(j = 0; j < 10000; j++) { k = 3000 for(k = 0; k < 10000; k++) { printf("%d ",i+j+k); } } } return 0; }
- 19. Conditional Breakpoints //file_read.c input.dat #include <stdio.h> #include <string.h> id animal int main(void) 1 CAT { 2 SHEEP FILE *input_fp = NULL; char buff[255]; 3 WOLF int id = 0; 4 DOG char animal[16]; input_fp = fopen("input.dat","r"); 5 MONKEY 6 EAGLE while(fgets(buff,sizeof(buff)-1,input_fp) != NULL) { 7 MAN sscanf(buff,"%d %s %*[^n]",&id,animal); printf("Animal at pos %d is %sn",id,animal); } fclose(input_fp); return 0; } How do I stop the id = 4 execution when
- 21. Conditional Breakpoints //file_read.c input.dat #include <stdio.h> #include <string.h> id animal int main(void) 1 CAT { 2 SHEEP FILE *input_fp = NULL; char buff[255]; 3 WOLF int id = 0; 4 DOG char animal[16]; input_fp = fopen("input.dat","r"); 5 MONKEY 6 EAGLE while(fgets(buff,sizeof(buff)-1,input_fp) != NULL) { 7 MAN sscanf(buff,"%d %s %*[^n]",&id,animal); printf("Animal at pos %d is %sn",id,animal); } fclose(input_fp); return 0; } How do I stop the animal = MAN execution when
- 23. Final Words Prevention is better than cure Always strive for simplicity in your code. A good measure of simplicity lies in the number of instructions used to get the job done. Lesser the better. Less conditional statements (if, else if , else) More repeatable statements (loops, function recursion ) Less nested statements (loop in a loop, nested ifs) Learn and be aware of standard library functions Don’t re-invent the wheel, many open source library are available to solve various problems in the scientific domain
- 24. what next? File I/O Data types Standard & structures C Library Pointers & Memory Allocation Debugging Macro and Version Pre Processor Management Multi file projects
- 25. A man who wants to lead an orchestra must turn his back on the crowd - Max Lucado thank you