如何解析整数命令行参数使用C？ [英] How to parse integer command line arguments in C?
问题描述
我想一个用户通过其中两个参数或留空。例如：
I would like a user to pass either two parameters or leave it blank. For instance:
./program 50 50
或
./program
当我试图用 INT主（INT ARGC，CHAR *的argv []），第一件事情我已经做了修改的char *的argv [] 到为int *的argv [] ，但没有奏效。我想是从用户只是为0和100之间的输入的两个整数因此，如果它不是两个整数那么它应该给出一个错误。
When I tried to use int main(int argc, char *argv[]), first thing I have done was to change char *argv[] to int *argv[] but it did not work. What I want is from the user is just to enter two integers between 0 and 100. So if it is not two integers then it should give an error.
我是那种想放弃了与类型错误（为我所用的C＃程序），但不管我进入，ARGV [1]是'符'类型的所有时间。
I was sort of thinking to give out an error with types (as I used to program on C#) but whatever I enter, argv[1] would be 'char' type all the time.
所以我所做的就是
for (int i = 0; i <= 100; i++)
{
//printf("%d", i);
if (argv[1] == i)
{
argcheck++;
printf("1st one %d\n", i);
}
else if (argv[2] == i)
{
argcheck++;
printf("2nd one %d\n", i);
}
这不能正常工作。此外，它提供了编译时警告，但如果我改变的argv 与的atoi（ARGV [1]）的实例，那么它给了分段故障（核心转储）错误。
This does not work as well. Also it gives warning when compiling, but if I change argv with atoi(argv[1]) for instance, then it gives a Segmentation fault (core dumped) error.
我需要一种简单的方式来解决这个问题。
I need a simple way to solve this problem.
编辑：
所以我固定的atoi（），为什么它被赋予段故障的原因是因为我是用null值尝试它，当我没有参数。所以我固定它通过增加一个额外COND。但现在的问题是，如果该值假设
So I fixed with atoi(), the reason why it was giving segmentation fault was because I was trying it with null value when I have no parameter. So I fixed it up by adding an extra cond. But now the problem is if the value is let's say
./program asd asd
然后的atoi的输出（ARGV [1]）将是0。那么，有没有办法改变这个值？
Then the output of atoi(argv[1]) would be 0. So is there a way to change this value?
推荐答案
不要使用的atoi（）和不使用与strtol（）。 ATOI（）没有错误检查（如你发现了！），并与strtol（）必须错误检查使用全局errno变量，这意味着你必须给errno设置为0，然后调用与strtol（），然后再检查errno错误。更好的方法是使用的sscanf（），它也可以让你从一个字符串，而不仅仅是一个整数分析任何原始类型，它可以让你读花式格式（如十六进制）。
Don't use atoi() and don't use strtol(). Atoi() has no error checking (as you found out!) and strtol() has to be error-checked using the global errno variable, which means you have to set errno to 0, then call strtol(), then check errno again for errors. A better way is to use sscanf(), which also lets you parse any primitive type from a string, not just an integer, and it lets you read fancy formats (like hex).
例如，要分析从字符串整数1435：
For example, to parse integer "1435" from a string:
if (sscanf (argv[1], "%i", &intvar)!=1) { printf ("error - not an integer"); }
从字符串解析单个字符Z
To parse a single character 'Z' from a string
if (sscanf (argv[1], "%c", &charvar)!=1) { printf ("error - not a char"); }
从字符串解析漂3.1459
To parse a float "3.1459" from a string
if (sscanf (argv[1], "%f", &floatvar)!=1) { printf ("error - not a float"); }
要从一个字符串分析一个大的无符号十六进制整数0x332561
To parse a large unsigned hexadecimal integer "0x332561" from a string
if (sscanf (argv[1], "%xu", &uintvar)!=1) { printf ("error - not a hex integer"); }
如果您需要更多的错误处理比，使用正则表达式库。
If you need more error-handling than that, use a regex library.
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