[英]Read integers into an array in C
I'm trying to read a text file of integers into an array in C.我正在尝试将整数文本文件读入 C 中的数组。
My text file looks like this: (12 numbers/line)我的文本文件如下所示:(12 个数字/行)
5713 6936 8764 6702 8535 8654 8710 8332 4948 7627 5472 5311
7331 8719 6135 6672 5786 7113 5292 6923 5683 7020 8595 8606
6837 7003 7415 8372 8429 5726 8323 6442 8672 6488 6932 5884
6811 7785 7189 5531 6323 8561 8283 5114 6669 7217 8307 6599
6961 8695 6026 5580 6010 4954 8725 4955 5532 7736 5372 8712
8343 5375 5931 6449 8223 5844 5931 5307 5436 6405 8599 6302
8617 8222 5985 8216 5044 5259 6523 7526 8702 5878 7559 5366
5362 7393 6633 8781 6289 6470 5342 7278 5348 8677 5779 5763
5718 8678 6406 8774 5931 7324 6819 6393 5027 7545 8385 8795
8277 8059 6362 6980 5899 5828 6707 7149 5621 7287 5958 6506
6517 5710 5504 7070 8797 6840 7112 6063 7014 5419 7514 7431
The actual file has overall 1000 numbers实际文件总共有 1000 个数字
Currently, I am using the following code:目前,我正在使用以下代码:
int main(void){
FILE *my_file;
my_file = fopen("seals.txt", "r");
size_t size = word_conter(my_file);
int weight = 0;
int seals[size];
int i;
for(i = 0; i < size; i++){
if(fscanf(my_file, "%1d", &weight) == 1)
seals[i] = weight;
else break;
}
for(i = 0; i < size; i++){
printf("%d\t %d\n", i, seals[i]);
}
fclose(my_file);
return 0;
}
EDIT: Here is word_counter
:编辑:这是
word_counter
:
size_t word_conter(FILE *my_file){
if(my_file == NULL){
perror("Error in file");
exit(1);
}
size_t counter = 0, in_word = 0;
char ch;
while((ch = fgetc(my_file)) != EOF){
if(ch == ' ' || ch == '\n' || ch == '\t' || ch == '\0'){
if(in_word){
in_word = 0;
counter++;
}
}
else in_word = 1;
}
return counter;
}
Unfortunately, my output is:不幸的是,我的 output 是:
0 245589760
1 1
2 1
3 0
4 -497513808
5 32766
6 245022469
7 1
8 -497513808
9 32766
10 245022268
11 1
12 1
13 0
14 224894352
15 1
16 -497513744
17 32766
18 244994643
19 1
20 245557328
21 1
22 224894352
23 1
24 224879992
25 1
26 0
27 0
28 245584536
29 1
30 245616784
31 1
32 -497513712
33 32766
34 245024298
35 1
36 245557328
37 1
38 -799666472
39 22978
40 -497510096
And so on up to 999.以此类推,直到 999。
I have tried using both: fscanf(my_file, "%1d", &weight)
and fscanf(my_file, "%d", &weight)
but both didn't work.我已经尝试使用这两个:
fscanf(my_file, "%1d", &weight)
和fscanf(my_file, "%d", &weight)
但都没有工作。 I have read the manual about fscanf but still couldn't get it right.我已阅读有关 fscanf 的手册,但仍然无法正确理解。
Any help would be much appreciated!任何帮助将非常感激!
Second Edit :第二次编辑:
I used rewind()
and that did the trick!我使用了
rewind()
并且成功了!
In a nutshell, this is caused by reading through the data file twice in a row without calling rewind()
.简而言之,这是由于在没有调用
rewind()
的情况下连续两次读取数据文件造成的。
The problem occurs when fscanf()
reads the file for a second time without rewinding.当
fscanf()
在没有倒带的情况下第二次读取文件时会出现问题。 (first read is in word_conter()
function): (第一次读取是在
word_conter()
函数中):
if(fscanf(my_file, "%d", &weight) == 1)//2nd read on one file descriptor
seals[i] = weight;//program flow never gets here
else break;
This results in execution flow jumping directly to else break;
这导致执行流程直接跳转到
else break;
, then continuing to loop on printf()
and outputting the uninitialized array: int seals[size];
,然后继续循环
printf()
并输出未初始化的数组: int seals[size];
Also, the function word_conter
is susceptible to various inconsistencies data formatting might present within the file it is reading.此外,function
word_conter
容易受到其正在读取的文件中可能存在的各种不一致数据格式的影响。 Suggest stepping through code in a debugger to characterize exactly how this might be contributing to the problem.建议在调试器中单步执行代码,以准确描述这可能如何导致问题。
My suggestion is to call fopen()
and fclose
each once inside word_counter
, then re-call both again in the main function.我的建议是在
word_counter
中分别调用fopen()
和fclose
一次,然后在主 function 中再次调用两者。 This refactored version of size_t word_conter(FILE *my_file)
supports this approach. size_t word_conter(FILE *my_file)
的这个重构版本支持这种方法。 (written to accommodate file containing 12 numbers per line as per mentioned in comments): (编写以容纳每行包含 12 个数字的文件,如评论中所述):
size_t word_counter(char *filename)
{
char line[260] = {0};
char *tok = NULL;
int count = 0;
FILE *fp = fopen(filename, "r");
if(fp)
{
while(fgets(line, sizeof(line), fp))
{
tok = strtok(line, " \n");
while(tok)
{
count++;
tok = strtok(NULL, " \n");
}
memset(line, 0, sizeof(line));
}
fclose(fp);
}
return count;
}
Called in main as:在 main 中调用为:
size_t size = word_counter("seals.txt");
There is also an instance of using an incorrect format specifier can invoke undefined behavior还有一个使用不正确格式说明符的实例可以调用未定义的行为
For:为了:
int weight = 0;
The correct format specifier is "%d"
.正确的格式说明符是
"%d"
。 Either change:要么改变:
if(fscanf(my_file, "%1d", &weight) == 1)
to:至:
if(fscanf(my_file, "%d", &weight) == 1)
or change:或更改:
int weight = 0;
int seals[size];
to:至:
long weight = 0;
long seals[size];
( %ld
is used only for long
.) (
%ld
仅用于long
。)
Addressing each of these is likely to address the problem you are seeing.解决这些问题可能会解决您所看到的问题。 (However, because
word_conter()
is not shown in detail, there may be other issues.) (不过,由于
word_conter()
没有详细展示,可能还有其他问题。)
Word counter messes up on edge cases.字数计数器在边缘情况下搞砸了。
Look for transitions from space to non-space.寻找从空间到非空间的过渡。 Do not forget to
rewind()
.不要忘记
rewind()
。
size_t counter = 0;
bool in_word = false;
// char ch;
int ch;
while((ch = fgetc(my_file)) != EOF){
if (ch == ' ' || ch == '\n' || ch == '\t' || ch == '\0') { // better: if (isspace(ch)) {
in_word = false;
} else {
if (!in_word) counter++;
in_word = true;
}
}
rewind(my_file); // reset to the beginning
return counter;
Even better, just go through the file twice with the same format.更好的是,只需 go 以相同的格式通过文件两次。
size_t counter = 0;
while (fscanf(my_file, "%d", &weight) == 1) {
counter++;
}
rewind(my_file); // reset to the beginning
try to replace if(fscanf(my_file, "%1d", &weight) == 1)
with if(fscanf(my_file, "%d", &weight) != EOF)
尝试将
if(fscanf(my_file, "%1d", &weight) == 1)
替换为if(fscanf(my_file, "%d", &weight) != EOF)
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