The atof() function is defined in the stdlib.h header file. It helps to convert a given string argument(str) into a floating-point value ie type double.
double atof(const char *str); #where str should be a string
The atof() function takes a single parameter. In C language typecasting is supported by stdlib.h headerfile.
Parameter | Description | Required / Optional |
---|---|---|
str | the string having the representation of a floating-point number | Required |
The return value of atof() function is a floating-point number as a double value.
Input | Return Value |
---|---|
successful | double value |
invalid conversion | zero |
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
float f;
char st[20];
strcpy(st, "23333333");
f = atof(st);
printf("String is %s, Float value = %f\n", st, f);
strcpy(st, "Hi how are you");
f = atof(st);
printf("String is %s, Float value = %f\n", st, f);
return(0);
}
Output:
String is 23333333, Float value = 23333333.000000 String is Hi how are you, Float value = 0.000000
#include <stdio.h>
int main (){
char x[10] = "3.14";
float pi = atof(x);
printf("pi value is %f\n", pi);
return 0;
}
Output:
pi value is 3.140000