[英]How do I read a string until a comma in C89?
I am trying to read a CSV file in c89
using scanf
:我正在尝试使用scanf
读取c89
中的 CSV 文件:
FOO,2,3
BAR,5,4
...
This is what I have tried:这是我尝试过的:
#include <stdio.h>
int main() {
char code[10];
double a,b;
while( scanf("%s,%lf,%lf", code, &a, &b)!=EOF ) {
printf("> %s\n", code);
printf("> %s,%lf,%lf\n", code, a, b);
}
return 0;
}
This is the output I get:这是我得到的 output:
$ ./a.out
A,2,3
> A,2,3
> A,2,3,0.000000,0.000000
B,5,4
> B,5,4
> B,5,4,0.000000,0.000000
$
This is the output I was expecting from the above code:这是我从上面的代码中期待的 output:
$ ./a.out
A,2,3
> A
> A,2.000000,3.000000
B,5,4
> B
> B,5.000000,4.000000
$
Edit编辑
As per the comment provided I have tried:根据提供的评论,我尝试过:
#include <stdio.h>
int main() {
char code[10];
double a,b;
while( scanf("%9[^,],%lf,%lf", code, &a, &b)!=EOF ) {
printf("> %s\n", code);
printf("> %s,%lf,%lf\n", code, a, b);
}
return 0;
}
And I get:我得到:
$ cat > test.txt
A,2,3
B,4,5
C,5,6
$ cat test.txt | ./a.out
> A
> A,2.000000,3.000000
>
B
>
B,4.000000,5.000000
>
C
>
C,5.000000,6.000000
>
>
,5.000000,6.000000
$
Apparently the first record is properly processed but not the subsequent ones.显然,第一条记录已正确处理,但后续记录未正确处理。
Also I have the question about what the 9
does and if the whole %9[^,]
is part of c89
.我也有关于9
做什么以及整个%9[^,]
是否是c89
的一部分的问题。
I found a workaround that is reaching each line into a buffer and replacing the commas by spaces first, then I apply the %s
.我找到了一种解决方法,将每一行放入缓冲区并首先用空格替换逗号,然后应用%s
。
#include <stdio.h>
int main() {
char line[256];
char code[10];
double a,b;
while(scanf("%s", line) != EOF) {
/* REPLACE ALL , BY SPACES TO SIMPLIFY SCANF USAGE */
char *p = line;
while(*p!='\0') {
if(*p==',') {
*p = ' ';
}
p++;
}
sscanf(line,"%s %lf %lf", code, &a, &b);
printf("> %s\n", code);
printf("> %s,%lf,%lf\n", code, a, b);
}
return 0;
}
Not sure if it is the most elegant solution, but improves readability of the scanf part.不确定它是否是最优雅的解决方案,但提高了 scanf 部分的可读性。
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