C atof() function
C atof() function - Convert character string to float
The atof() function is used to convert a character string to a double-precision floating-point value.
Syntax:
double atof(const char *str)
Parameters:
Name | Description | Required /Optional |
---|---|---|
str | String to be converted. | Required |
Return value from atof()
- Returns a double value that is produced by interpreting the input characters as a number.
- If the function cannot convert the input to a value of that type return value is 0.
Example: atof() function
The following example shows the usage of atof() function.
#include <stdlib.h>
#include <stdio.h>
int main(void)
{
double x;
char *s;
s = "-3423.12E-15";
printf("String value: %s",s);
x = atof(s);
printf("\nDouble-precision floating-point value = %.4e\n",x);
s = "+3423.12E-15";
printf("\nString value: %s",s);
x = atof(s);
printf("\nDouble-precision floating-point value = %.4e\n",x);
s = "3423.12E-15";
printf("\nString value: %s",s);
x = atof(s);
printf("\nDouble-precision floating-point value = %.4e\n",x);
s = "4567.456";
printf("\nString value: %s",s);
x = atof(s);
printf("\nDouble-precision floating-point value = %.4e\n",x);
s = "4567";
printf("\nString value: %s",s);
x = atof(s);
printf("\nDouble-precision floating-point value = %.4e\n",x);
}
Output:
String value: -3423.12E-15 Double-precision floating-point value = -3.4231e-012 String value: +3423.12E-15 Double-precision floating-point value = 3.4231e-012 String value: 3423.12E-15 Double-precision floating-point value = 3.4231e-012 String value: 4567.456 Double-precision floating-point value = 4.5675e+003 String value: 4567 Double-precision floating-point value = 4.5670e+003
C Programming Code Editor:
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C Programming: Tips of the Day
What's the point of const pointers?
const is a tool which you should use in pursuit of a very important C++ concept:
Find bugs at compile-time, rather than run-time, by getting the compiler to enforce what you mean.
Even though it does not change the functionality, adding const generates a compiler error when you're doing things you didn't mean to do. Imagine the following typo:
void foo(int* ptr) { ptr = 0;// oops, I meant *ptr = 0 }
If you use int* const, this would generate a compiler error because you're changing the value to ptr. Adding restrictions via syntax is a good thing in general. Just don't take it too far -- the example you gave is a case where most people don't bother using const.
Ref : https://bit.ly/33Cdn3Q
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