OK to cut a long story short I have a program which crashes when it returns from a function call.
Hence I need to be able to examine the return address to see when it changes.
Bit of a weird problem, this program used to work, I have made a few changes but not the sort that would cause this problem (I think).
The function has been called several hundred times before and returned OK (with pretty much the same parameters passed to it).
OK I have decided to not pass any parameters to it and make them global, will see what happens!!!!
One possibility is that the function is returning the address of a local variable - which can eventually cause the caller to crash when it dereferences (uses) the object at that address. It doesn't matter if your function has been called millions of times before - those previous calls might have done something that wasn't detected by the operating system.
However, the more likely possibility is some other code is the cause. If some other code executed before your function is tromping memory used by your function, it will eventually cause your function to crash.
Either way, the problem might appear to go away if you make parameters global - but that does not mean the problem has been eliminated. Restructuring memory used by your program (which is what you will be doing if you make things global) changes the symptom, not the cause.
Without seeing a sample of code that illustrates your problem, it is impossible to speculate further.
Try providing a SMALL, COMPLETE, and COMPILABLE sample of code that illustrates your problem. In the process of producing that sample, you might have an "aha!" moment, and find the problem. If not, other people will have a chance of helping you.
Have you tried running the program with the aid of a debugger? I don't see how changing a function to depend on global variables could really be the cause of the problem. Depending on global state should be avoided if possible.
OK I have made the values global and the problem is still there.
It could be a few things
How are you examining the return address?
Fact - Beethoven wrote his first symphony in C
This was a program I kind of hacked together from another very similar program.
But it was working for a good while.
I kind of agree with what grumpy says, some memory is being over written.
It a fairly big program to list here.
This is some debug code of the fail.
This is the end of the function, note I have debug code in there.Code:george_shrub posts big blind [$0.10 USD]. VALUE<0.10 USD].> betval <0.100000> string <0.10 USD].> <-1> KKJ3421ff player no <4> KKJ342ggw KKJ342ggjj Exiting due to signal SIGSEGV General Protection Fault at eip=000089ac eax=e36c38b0 ebx=000193ec ecx=000193ec edx=e36c38b0 esi=02feb414 edi=000193f7 ebp=02feaa58 esp=02feaa54 program=Exiting due to signal SIGSEGV
Code:printf("\n KKJ342ggw "); fflush(stdout); raiseflag=0; printf("\n KKJ342ggjj "); fflush(stdout); }
OK This is the whole of the function
Code:totalit() { float tempval; int tmp; pos++; // printf("\n PID valtemp vals %f start !!", pname[cpid[pid_no]].tempstack ); // for(tmp=pos; ((var1[tmp]>='0' && var1[tmp]<='9') || var1[tmp]==',');tmp++){ // if (var1[tmp]==',') strcpy(&var1[tmp],&var1[tmp+1]); // } sscanf(&var1[pos],"%f",&betval); printf("\n\n%s VALUE<%s>",var1, &var1[pos]); fflush(stdout); printf("\nbetval <%f> string <%s> <%d>", betval, &var1[pos], signeg);fflush(stdout); csitoutid[player_no]=0; if (strcmp( pname[cpid[player_no]].name, PID)==0) flastard=1; else flastard=0; if (anteflag==0) { if (cfid[player_no]==0) { /*first time*/ cfid[player_no]=1; if (cbid[player_no]==0) /*not blind */ { pname[cpid[player_no]].tookpart++; if (table_size>=5) pname[cpid[player_no]].tookpart5++; if (table_size>=8) pname[cpid[player_no]].tookpart8++; if (table_size>=3) pname[cpid[player_no]].tookpart3++; } } } anteflag=0; //clear anteflag every time tempval=betval; if (raiseflag) { /* betval-=tempstack2; */ // if (pid_no==cpid[player_no]){ printf("\nRaise vals %f %f !!", betval, pname[cpid[player_no]].tempstack ); // } betval+=pname[cpid[player_no]].tempstack; printf("\nRaise flag set <%f>",pname[cpid[player_no]].tempstack); } if (signeg) { // printf("\n Total -%f",betval); // printf("\n signev"); printf("\n KKJ3421ff player no <%d> ", player_no ); fflush(stdout); pname[cpid[player_no]].stack-=betval; pname[cpid[player_no]].tempstack-=betval; t_in+=betval; st_in+=betval; if (flastard) p_in-=betval; } else { // printf("\n sigpos %f",betval); // printf("\n Total +%f",betval); printf("\n KKJ3421ww "); fflush(stdout); pname[cpid[player_no]].stack+=betval; printf("\n KKJ3421wxxzw "); fflush(stdout); pname[cpid[player_no]].tempstack+=betval; t_out+=betval; st_out+=betval; printf("\n KKJ3421wccw "); fflush(stdout); if (flastard) p_in+=betval; } //} /* if (var1[pos]=='$') { if (signneg) { pname[cpid[player_no]].dolstack-=betval; pname[cpid[player_no]].tempval-=betval; if (flastard) d_in-=betval; } else { pname[cpid[player_no]].dolstack+=betval; pname[cpid[player_no]].tempval+=betval; if (flastard) d_in+=betval; } } */ /* printf("\nPlayer 5b %f\n",pname[cpid[player_no]].stack); */ // printf("\n PID valtemp vals %f start !!", pname[cpid[pid_no]].tempstack ); printf("\n KKJ342ggw "); fflush(stdout); raiseflag=0; printf("\n KKJ342ggjj "); fflush(stdout); }
this is the call to the function, just posting it might help me think lol.
Code:printf("\n debug21 <%s>",&var1[19+namelen]); sscanf(&var1[19+namelen],"%f%[^\n]\n",&betval,var3); pos=18+namelen; signeg=MINUS; totalit(); break; }
So basically I think something is overwriting stuff elsewhere.
How are you global variables declared?
Fact - Beethoven wrote his first symphony in C
Originally Posted by Click_here
Code:int pos,signeg;
Pretty sure the problem lies else where, I think I have noticed an "issue"
... That doesn't account for all the variables that you have used
I'd say that you are going out of bounds on one of those arrays
No worries.Pretty sure the problem lies else where, I think I have noticed an "issue"
Fact - Beethoven wrote his first symphony in C
