为什么我在 C 中遇到段错误？
Why am I getting a seg fault in C?
https://github.com/KRegan82/Tinkering/blob/master/sierpinskiBMP.c
（2017-11-05 检索到的代码 - 可能与原始代码不同，这是问题中需要代码的另一个原因。）
#include <stdio.h>
#include <cs50.h>
#include <stdlib.h>
#include <math.h>
#include <stdint.h>
// data types for the standard MS sruct values for the headers
typedef uint8_t BYTE;
typedef uint32_t DWORD;
typedef int32_t LONG;
typedef uint16_t WORD;
//bmp file header struct
typedef struct
{
WORD bfType;
DWORD bfSize;
WORD bfReserved1;
WORD bfReserved2;
DWORD bfOffBits;
} __attribute__((__packed__))
BITMAPFILEHEADER;
//bmp info header struct
typedef struct
{
DWORD biSize;
LONG biWidth;
LONG biHeight;
WORD biPlanes;
WORD biBitCount;
DWORD biCompression;
DWORD biSizeImage;
LONG biXPelsPerMeter;
LONG biYPelsPerMeter;
DWORD biClrUsed;
DWORD biClrImportant;
} __attribute__((__packed__))
BITMAPINFOHEADER;
//bmp pixel struct
typedef struct
{
BYTE rgbtBlue;
BYTE rgbtGreen;
BYTE rgbtRed;
} __attribute__((__packed__))
RGBTRIPLE;
// this program is designed to 'build' a sierpinski triangle of n layers given the users input. triangle built from top down using 2 x 2 pixel structure
// the structs above are completely 'borrowed' from the team at harvards cs50 class, whose mobile IDE is also wehre I wrote this
// and a special thank you to Irene Naya and Aditya Singhania two strangers on facebook for whom I couldn't have made this without
int main(void)
{
//prompt for and store height (in 2x2 pixel size)
fprintf(stderr, "How many layers do you want? ");
int n = get_int();
//setup paramaters to write to .bmp file and filename
char ofName[21];
sprintf(ofName,"sierpinski%05i.bmp",n);
FILE *outfile = fopen(ofName,"w");
// setup file header and info header assignments
BITMAPFILEHEADER bf;
BITMAPINFOHEADER bi;
//calculate header and header info values to write using structs in bmp.h
bi.biWidth = (n * 2) + 4;
bi.biHeight = 0 -((n * 2) + 4);
//calculate padding that will be needed
int pad = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
// assign new image size
bi.biSizeImage = abs(bi.biHeight) * ((bi.biWidth * sizeof(RGBTRIPLE)) + pad);
// assign new file header parameters
bf.bfType = 0x4d42;
bf.bfReserved1 = 0;
bf.bfReserved2 = 0;
bf.bfOffBits = 0x36;
//assign new info header parameters
bi.biSize = 0x28;
bi.biPlanes = 1;
bi.biBitCount = 24;
bi.biCompression = 0;
bi.biXPelsPerMeter = 0xb12;
bi.biYPelsPerMeter = 0xb12;
bi.biClrUsed = 0;
bi.biClrImportant = 0;
// assign new file size
bf.bfSize = bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
// write outfile's BITMAPFILEHEADER
fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outfile);
// write outfile's BITMAPINFOHEADER
fwrite(&bi, sizeof(BITMAPINFOHEADER), 1, outfile);
//necessary variables for triangle algorithm
long long body[n][n];
int print = 0;
//create rgp triple for manipulation
RGBTRIPLE pixel;
//add buffer lines to top of .bmp
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
// second layer of top buffer lining
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
// iterate over the area and print necessary digits
for(int i = 0; i < n ; i++)
{
// blank space that borders triangle value
int blankCount = (n + 1) - i;
//write blank space surrounding start of triangle
for(int j = 0; j < blankCount; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//draw first line of this rows triangle values
for(int j = 0; j<=i; j++)
{
if (j == 0 || i == j)
{
print = 1;
body[i][j] = 1;
}
else if( body[i-1][j-1] + body[i-1][j] == 2 || body[i-1][j-1] + body[i-1][j] == 0)
{
print = 0;
body[i][j] = 0;
}
else if(body[i-1][j-1] + body[i-1][j] == 1 )
{
print = 1;
body[i][j] = 1;
}
if ( print == 0)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
else if (print == 1)
{
pixel.rgbtRed = 0x00;
pixel.rgbtBlue = 0x00;
pixel.rgbtGreen = 0x00;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
}
// proceeding blank space bordering back end of triangle
for(int j = 0; j < blankCount; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add back in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
//this is really just a second iteration of drawing the same row. each row has to be drawn twice because each element is 2 pixels by two pixels
for(int j = 0; j <blankCount ; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
for(int j = 0; j<=i; j++)
{
if (j == 0 || i == j)
{
print = 1;
body[i][j] = 1;
}
else if( body[i-1][j-1] + body[i-1][j] == 2 || body[i-1][j-1] + body[i-1][j] == 0)
{
print = 0;
body[i][j] = 0;
}
else if(body[i-1][j-1] + body[i-1][j] == 1 )
{
print = 1;
body[i][j] = 1;
}
if ( print == 0)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
else if (print == 1)
{
pixel.rgbtRed = 0x00;
pixel.rgbtBlue = 0x00;
pixel.rgbtGreen = 0x00;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
}
for(int j = 0; j < blankCount; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
}
// add buffer lines to bottom of .bmp
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
// just tidying up here
fclose(outfile);
return 0;
}
我正在学习 CS50 class，并编写了这个程序来将 Sierpinski 三角形输出到用户给定高度的 .bmp 文件。它可以很好地生成最多和超过 512 行的任何内容，但是在 1024（下一个完整的三角形高度）我遇到了段错误。
不确定为什么会这样，是不是因为我从堆栈而不是堆中分配内存？任何帮助将不胜感激。
这是我初始化数组的代码段，该数组跟踪每个像素应包含的值。
long long body[n][n];
我将其更改为 long long 希望可以解决问题，但显然是另外一回事。困惑。
您的 body[n][n] 数组太大，无法在堆栈上分配。
您可以在堆上分配它，而不是在堆上分配，这样您就不会受到大小的限制。
有关如何动态分配二维数组的信息，请参见上一个答案：
Allocate memory 2d array in function C
https://github.com/KRegan82/Tinkering/blob/master/sierpinskiBMP.c
（2017-11-05 检索到的代码 - 可能与原始代码不同，这是问题中需要代码的另一个原因。）
#include <stdio.h>
#include <cs50.h>
#include <stdlib.h>
#include <math.h>
#include <stdint.h>
// data types for the standard MS sruct values for the headers
typedef uint8_t BYTE;
typedef uint32_t DWORD;
typedef int32_t LONG;
typedef uint16_t WORD;
//bmp file header struct
typedef struct
{
WORD bfType;
DWORD bfSize;
WORD bfReserved1;
WORD bfReserved2;
DWORD bfOffBits;
} __attribute__((__packed__))
BITMAPFILEHEADER;
//bmp info header struct
typedef struct
{
DWORD biSize;
LONG biWidth;
LONG biHeight;
WORD biPlanes;
WORD biBitCount;
DWORD biCompression;
DWORD biSizeImage;
LONG biXPelsPerMeter;
LONG biYPelsPerMeter;
DWORD biClrUsed;
DWORD biClrImportant;
} __attribute__((__packed__))
BITMAPINFOHEADER;
//bmp pixel struct
typedef struct
{
BYTE rgbtBlue;
BYTE rgbtGreen;
BYTE rgbtRed;
} __attribute__((__packed__))
RGBTRIPLE;
// this program is designed to 'build' a sierpinski triangle of n layers given the users input. triangle built from top down using 2 x 2 pixel structure
// the structs above are completely 'borrowed' from the team at harvards cs50 class, whose mobile IDE is also wehre I wrote this
// and a special thank you to Irene Naya and Aditya Singhania two strangers on facebook for whom I couldn't have made this without
int main(void)
{
//prompt for and store height (in 2x2 pixel size)
fprintf(stderr, "How many layers do you want? ");
int n = get_int();
//setup paramaters to write to .bmp file and filename
char ofName[21];
sprintf(ofName,"sierpinski%05i.bmp",n);
FILE *outfile = fopen(ofName,"w");
// setup file header and info header assignments
BITMAPFILEHEADER bf;
BITMAPINFOHEADER bi;
//calculate header and header info values to write using structs in bmp.h
bi.biWidth = (n * 2) + 4;
bi.biHeight = 0 -((n * 2) + 4);
//calculate padding that will be needed
int pad = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
// assign new image size
bi.biSizeImage = abs(bi.biHeight) * ((bi.biWidth * sizeof(RGBTRIPLE)) + pad);
// assign new file header parameters
bf.bfType = 0x4d42;
bf.bfReserved1 = 0;
bf.bfReserved2 = 0;
bf.bfOffBits = 0x36;
//assign new info header parameters
bi.biSize = 0x28;
bi.biPlanes = 1;
bi.biBitCount = 24;
bi.biCompression = 0;
bi.biXPelsPerMeter = 0xb12;
bi.biYPelsPerMeter = 0xb12;
bi.biClrUsed = 0;
bi.biClrImportant = 0;
// assign new file size
bf.bfSize = bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
// write outfile's BITMAPFILEHEADER
fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outfile);
// write outfile's BITMAPINFOHEADER
fwrite(&bi, sizeof(BITMAPINFOHEADER), 1, outfile);
//necessary variables for triangle algorithm
long long body[n][n];
int print = 0;
//create rgp triple for manipulation
RGBTRIPLE pixel;
//add buffer lines to top of .bmp
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
// second layer of top buffer lining
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
// iterate over the area and print necessary digits
for(int i = 0; i < n ; i++)
{
// blank space that borders triangle value
int blankCount = (n + 1) - i;
//write blank space surrounding start of triangle
for(int j = 0; j < blankCount; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//draw first line of this rows triangle values
for(int j = 0; j<=i; j++)
{
if (j == 0 || i == j)
{
print = 1;
body[i][j] = 1;
}
else if( body[i-1][j-1] + body[i-1][j] == 2 || body[i-1][j-1] + body[i-1][j] == 0)
{
print = 0;
body[i][j] = 0;
}
else if(body[i-1][j-1] + body[i-1][j] == 1 )
{
print = 1;
body[i][j] = 1;
}
if ( print == 0)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
else if (print == 1)
{
pixel.rgbtRed = 0x00;
pixel.rgbtBlue = 0x00;
pixel.rgbtGreen = 0x00;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
}
// proceeding blank space bordering back end of triangle
for(int j = 0; j < blankCount; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add back in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
//this is really just a second iteration of drawing the same row. each row has to be drawn twice because each element is 2 pixels by two pixels
for(int j = 0; j <blankCount ; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
for(int j = 0; j<=i; j++)
{
if (j == 0 || i == j)
{
print = 1;
body[i][j] = 1;
}
else if( body[i-1][j-1] + body[i-1][j] == 2 || body[i-1][j-1] + body[i-1][j] == 0)
{
print = 0;
body[i][j] = 0;
}
else if(body[i-1][j-1] + body[i-1][j] == 1 )
{
print = 1;
body[i][j] = 1;
}
if ( print == 0)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
else if (print == 1)
{
pixel.rgbtRed = 0x00;
pixel.rgbtBlue = 0x00;
pixel.rgbtGreen = 0x00;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
}
for(int j = 0; j < blankCount; j++ )
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
}
// add buffer lines to bottom of .bmp
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
for(int i = 0; i< ((n * 2) + 4); i++)
{
pixel.rgbtRed = 0xff;
pixel.rgbtBlue = 0xff;
pixel.rgbtGreen = 0xff;
fwrite(&pixel, sizeof(RGBTRIPLE), 1, outfile);
}
//add padding in if necessary
for (int l = 0; l < pad; l++)
{
fputc(0x00, outfile);
}
// just tidying up here
fclose(outfile);
return 0;
}
我正在学习 CS50 class，并编写了这个程序来将 Sierpinski 三角形输出到用户给定高度的 .bmp 文件。它可以很好地生成最多和超过 512 行的任何内容，但是在 1024（下一个完整的三角形高度）我遇到了段错误。
不确定为什么会这样，是不是因为我从堆栈而不是堆中分配内存？任何帮助将不胜感激。
这是我初始化数组的代码段，该数组跟踪每个像素应包含的值。
long long body[n][n];
我将其更改为 long long 希望可以解决问题，但显然是另外一回事。困惑。
您的 body[n][n] 数组太大，无法在堆栈上分配。 您可以在堆上分配它，而不是在堆上分配，这样您就不会受到大小的限制。 有关如何动态分配二维数组的信息，请参见上一个答案： Allocate memory 2d array in function C