Question

Here is the code snippet which I want to debug:
When I try to debug using GDB, after the loop gets over for i = 0, it does not jump to the very first line inside the loop for i = 1. Instead it jumps to another line in the middle and then jumps to the first line. I am not able to figure out why and how to fix it. Please give me your inputs.

for(i = 0; i < fileSum; i++)
{
    char *fileName ; //= NULL;
//  fileName = GetFileName(dataset->groundTruthFolder, trainImageFiles[i], dataset->groundTruthExtension);

    fileName = new char[strlen(dataset->groundTruthFolder) + strlen(trainImageFiles[i]) + strlen(dataset->groundTruthExtension) + 1];
    sprintf(fileName, "%s%s%s", dataset->groundTruthFolder, trainImageFiles[i], dataset->groundTruthExtension);
    printf("GetFileName: fileName-%s \n", fileName);


    LLabelImage groundTruth(fileName, domain);
//      delete[] fileName;
//      fileName = NULL;

    int width = groundTruth.GetWidth(), height = groundTruth.GetHeight();

    int subWidth = (width + subSample - 1) / subSample;
    int subHeight = (height + subSample - 1) / subSample;

    for(k = 0; k < subHeight; k++) for(j = 0; j < subWidth; j++)
    {
        unsigned char gtVal = groundTruth(j * subSample, k * subSample, 0);
        if(gtVal > 0) classCounts[gtVal - 1]++, total++;
        printf("k = %d,j = %d, gtVal = %d\n", k, j, gtVal);
    }
    int dummy = 0; 
    printf("i = %d\n", i);
}

Here is the gdb console’s snapshot:

Breakpoint 2, LDenseUnaryPixelPotential::InitTrainData (this=0x80aad08, trainImageFiles=...) at potential.cpp:665
665         int dummy = 0; 
(gdb) n
666         printf("i = %d\n", i); 
(gdb) n
i = 1
650         LLabelImage groundTruth(fileName, domain);
(gdb) n
640     for(i = 0; i < fileSum; i++)
(gdb) n

Breakpoint 1, LDenseUnaryPixelPotential::InitTrainData (this=0x80aad08, trainImageFiles=...) at potential.cpp:645
645         fileName = new char[strlen(dataset->groundTruthFolder) + strlen(trainImageFiles[i]) + strlen(dataset->groundTruthExtension) + 1];
(gdb) 

Please notice that, the control goes from 666 to 650 and then to 640, instead of going directly from 666 to 640.

Previously, I was compiling with -g option , now I compiled with -g -O0 option. Still the same problem persists.

Here is my Makefile:

CC  =   g++
OBJS    =   main.o
SOURCES =   main.cpp
LIBS    =       -lIL -pthread
EXE =   ale
FLAGS   = -g -O0 -Wno-write-strings

$(EXE): .
    $(CC) $(FLAGS) -c $(SOURCES) -o $(OBJS)
    $(CC) -o $(EXE) $(OBJS) $(LIBS)
clean: 
    rm -rf *.o ale

Answer 1

Actually, I debugged further and found that when the control reaches the end of the loop, the destructor of “LLabelImage” is being invoked to delete the data.