我试图编辑文本文件中的一行,但在编辑文件时出现了意外行为。我想做的是调整文本中看起来像的特定行(点:100)。在函数中,我通过ftell->user_point按值传递要调整的新硬币和文件的偏移量。我得到的输出很奇怪。我试着用编辑过的行将文件的其余部分复制到一个临时文件中,然后从复制到临时文件的点将其复制回原始文件。(这是ftell的用户点偏移量)。这是原始的封地,条目如下:
...
_______________________________________
nickname : geo
password : cuvctq
Name : george
Surname : papas
points : 100
participated :
past draws : 0
Chosen No. :
future draws : 0
Registered : Sun Feb 05 19:23:50 2012
...
第二次编辑后我得到的是:
...
_______________________________________
nickname : geo
password : cuvctq
Name : george
Surname : papaspoints : 98
participated :
past draws : 0
Chosen No. :
future draws : 0
Registered : Sun Feb 05 19:23:50 2012
...
At the end of the text i get one extra n after i edit the
file whch is something i dont want :/
所以进一步的编辑会破坏文本。。。我在行的末尾也得到了一个EXTRA,至少我认为是由于"r+"
模式,这也是我不想要的。。。
void coins_adjust(int coins_new,int user_point)
{
int lines,i,ln_point_copy;
char buffer[50],buff_copied[50];
FILE *lottary,*temp;
memset(buff_copied,' ',sizeof(char)*50);
lottary=fopen("customers.txt","r");
temp=fopen("temp.txt","w");
fseek(lottary,user_point,SEEK_SET);
for (lines=0;lines<5;lines++)
{
memset(buffer,' ',sizeof(char)*50);
if (lines==5)
ln_point_copy=ftell(lottary); //from TEMP to CUSTOMERS
fgets (buffer ,50 , lottary);
}
coins_new+=atoi(buffer+15);
strncpy(buff_copied,buffer,15); //copy 15 chars and fill with null
memset(buffer,' ',sizeof(char)*50);
itoa (coins_new,buffer,10); //fix the new line to be entered
strcat(buff_copied,buffer); //the edited line is as it is supposed
strcat(buff_copied,"n"); //to be with n at the end.
puts(buff_copied);
printf("%s",buff_copied);fflush(stdout);
fprintf(temp,"%s",buff_copied);
for(i=getc(lottary); i!=EOF; i=getc(lottary)) //copy to temp
{
putc(i, temp);
}
fclose(lottary);
fclose(temp);
temp=fopen("temp.txt","r");
lottary=fopen("customers.txt","r+");
fseek(lottary,ln_point_copy,SEEK_SET);
for(i=getc(temp); i!=EOF; i=getc(temp)) //copy until eof
{
putc(i, lottary);
}
fclose(lottary);fclose(temp);
}
我已经调试了这个程序,所有的东西似乎都能工作,至少在我存储行字符的数组中传递了什么值,但我不明白为什么当我试图将前一行的n
复制回原始行时,它会忽略它。。。当我复制回原始文件时,似乎有一个r
字符无法删除。。。提前谢谢。
我更多的是考虑这样的事情:
void change_points(int new_points)
{
FILE *input = fopen("customers.txt", "r");
FILE *output = fopen("temp.txt", "w");
char buffer[256];
while (fgets(buffer, sizeof(buffer), input))
{
/* Look for the correct line */
/* Can also use e.g. "if (strncmp(buffer, "points", 6) == 0)"
* if it's at the start of the line
*/
if (strstr(buffer, "points") != NULL)
{
int old_points;
sscanf(buffer, "%*s : %d ", &old_points);
/* Format how you like it */
fprintf(output, "%-13s: %dn", "points", new_points + old_points);
}
else
fputs(buffer, output);
}
fclose(output);
fclose(input);
/* The file "temp.txt" now contains the modifeed text */
/* Copy either using "fgets"/"fputs", or using "fread"/"fwrite" */
input = fopen("temp.txt", "r");
output = fopen("customers.txt", "w");
while (fgets(buffer, sizeof(buffer), input))
fputs(buffer, output);
fclose(output);
fclose(input);
}
它更短、更简单,也许更有效(逐行循环,而不是逐个字符循环),并且您要查找的行可以在文件中的任何位置,而不知道它的确切位置。