[英]Checking user input for numbers
In my main function, I have the following: 在主要功能中,我具有以下功能:
int main(){
FILE *fp;
char ch;
char name[100];
printf("Create file with name: ");
scanf("%s", &name);
fp = fopen(name, "w");
printf("Enter data to be stored in the file: ");
while((ch=getchar())!=EOF){
if(isNumeric(ch)){
putc(ch,fp);
}
}
fclose(fp);
return 0;
}
Which creates a file and stores data (by the user till the end of the input stream or Ctrl+Z) in it with getchar()
. 它使用getchar()
创建文件并在其中存储数据(由用户直到输入流或Ctrl + Z的末尾 getchar()
。 I want to check if the supplied data has been numerical but I'm hitting a rock. 我想检查所提供的数据是否为数字,但是我遇到了麻烦。 I've read many topics and all answers suggest isdigit()
but it doesn't validate numbers with a floating point. 我已经阅读了许多主题,所有答案都建议使用isdigit()
但它不能验证带有浮点数的数字。 Here's my isNumeric()
function: 这是我的isNumeric()
函数:
int isNumeric (const char * s)
{
if (s == NULL || *s == '\0' || isspace(*s))
return 0;
char * p;
strtod (s, &p);
return *p == '\0';
}
The fundamental problem here is that isNumeric
is designed to determine whether a string of characters is a valid number, but you're only giving isNumeric
one character at a time. 此处的根本问题是isNumeric
旨在确定字符串是否为有效数字,但是您一次只给isNumeric
一个字符。
To fix the problem, you need a char
array that stores characters until you reach a point where the array should contain a complete number. 要解决此问题,您需要一个存储字符的char
数组,直到到达该数组应包含完整数字的位置为止。 Then check the array with isNumeric
. 然后使用isNumeric
检查数组。
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