/* Exercise 4.2 from "The C programming language" book by K&R */
#include <stdio.h>
#include <ctype.h>
#define MAXLINE 100
double atof(char s[])
{
double val, power, degree;
int i, sign, sign2;
int counter;
for (i = 0; isspace(s[i]); i++)
;
sign = (s[i] == '-') ? -1 : 1;
if (s[i] == '+' || s[i] == '-')
i++;
for (val = 0.0; isdigit(s[i]); i++)
val = 10.0 * val + (s[i] - '0');
if (s[i] == '.')
i++;
for (power = 1.0; isdigit(s[i]); i++) {
val = 10.0 * val + (s[i] - '0');
power *= 10;
}
if (s[i] == 'e' || s[i] == 'E')
i++;
else
return sign * val / power;
sign2 = (s[i++] == '-') ? -1 : 1;
counter = 0;
for (degree = 1.0; counter < s[i] - '0'; counter++)
degree *= 10;
if (sign2 > 0)
return degree * sign * val / power;
else
return (sign * val / power) / degree;
}
int mygetline(char s[], int lim)
{
int c, i;
i = 0;
while (--lim > 0 && (c=getchar()) != EOF && c != '\n')
s[i++] = c;
if (c == '\n')
s[i++] = c;
s[i] = '\0';
return i;
}
int main(void)
{
double sum, atof(char []);
char line[MAXLINE];
int mygetline(char line[], int max);
sum = 0;
while (mygetline(line, MAXLINE) > 0)
printf("\t%g\n", sum += atof(line));
return 0;
}
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