[英]Reading in file leads to seg fault
So I've got a text file: 所以我有一个文本文件:
5f6
2f8
2f2
And I'm reading in the values : 5,6,2,8,2,2 where the first two numbers are always rows x columns, then I'm trying to draw rectangles in retrospect to the files values (This works, but after running the program and when it prints them, it seg faults). 我正在读取以下值:5,6,2,8,2,2,其中前两个数字始终是行x列,然后我试图回想起对文件值绘制矩形(这可行,但是在运行该程序并打印它们之后,将出现段错误)。
#include <stdio.h>
#include <ncurses.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char * argv[])
{
initscr();
cbreak();
noecho();
char str[100];
static char * row;
static char * col;
static int i;
static int j;
static int k;
static int x;
static int y;
int count = 0;
FILE* file;
file = fopen(argv[1],"r");
if(file == NULL)
{
mvprintw(0,0,"File returns null pointer");
exit(1);
}
while(!feof(file))
{
fgets(str,100,file);
row = strtok(str,"x");
col = strtok(NULL," \n");
x = atol(row);
y = atol(col);
for(j=0;j<x;j++)
{
for(k=0;k<y;k++)
{
mvprintw(k+5,j+5+count,".");
refresh(); //Space out drawing each rectangle? so they don't overlap
}
}
count+=5;
}
fclose(file);
getch();
endwin();
return (0);
}
I'm not really sure on how to proceed here, how would I go about eliminating this seg fault, and possibly spacing out the resultant drawing (The count variable doesn't seem to do it). 我不太确定如何进行此操作,如何消除此段错误,并可能将生成的图形间隔开(count变量似乎不执行此操作)。
Your segmentation fault is because you are not checking whether strtok()
returned NULL
and you still dereference the pointer with atol()
, this is an example of how to do it correctly 您的分段错误是因为您没有检查strtok()
是否返回NULL
并且仍使用atol()
取消引用指针,这是如何正确执行此操作的示例
#include <stdio.h>
#include <ncurses.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char * argv[])
{
char str[100];
int j;
int k;
int count;
FILE *file;
file = fopen(argv[1],"r");
if (file == NULL)
{
mvprintw(0, 0, "File returns null pointer");
return 1;
}
initscr();
cbreak();
noecho();
count = 0;
while(fgets(str, sizeof(str), file) != NULL)
{
char *endptr;
char *row;
char *col;
int x;
int y;
row = strtok(str, "f");
if (row == NULL)
{
fprintf(stderr, "`%s' does not contain `f'\n", str);
continue;
}
col = strtok(NULL, " \n");
if (col == NULL)
{
fprintf(stderr, "`%s' caused an unexpected error\n", str);
continue;
}
x = strtol(row, &endptr, 10);
if (*endptr != '\0')
{
fprintf(stderr, "Cannot convert `%s' to integer\n", row);
continue;
}
y = strtol(col, &endptr, 10);
if (*endptr != '\0')
{
fprintf(stderr, "Cannot convert `%s' to integer\n", col);
continue;
}
for (j = 0 ; j < x ; j++)
{
for (k = 0 ; k < y ; k++)
{
mvprintw(k + 5, j + 5 + count, ".");
refresh();
}
}
count+=5;
}
fclose(file);
getch();
endwin();
return 0;
}
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