C Programming Code Examples
C > Small Programs Code Examples
The `Eta' function
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/* The `Eta' function */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#define PACKAGE "eta"
#define VERSION "0.0.1"
#define MAXLINE 1024
/* status epilepticus, print help and exit with exval */
void print_help(int exval);
/* print program version and exit with exval */
void print_version(int exval);
/* `\056' `float' detection ? */
/* returns -1 on error, 1 on `no dot', 0 on `dot' */
int is_float(char *val);
int main(int argc, char *argv[]) {
char line[MAXLINE]; /* fgets buff */
int overview_flag = 0; /* print overview only */
int count = 0; /* nr of input elements */
float total = 0; /* eta */
float num = 0; /* the actual element */
int opt = 0; /* parsed opt nr */
float highest = 0; /* the lowest encounterd nr */
float lowest = 0; /* the highest encounterd nr */
/* option parser */
while((opt = getopt(argc, argv, "hve")) != -1) {
switch(opt) {
case 'h': /* print help and exit */
print_help(0);
case 'v': /* print version and exit */
print_version(0);
case 'e':
overview_flag = 1;
break;
case '?':
fprintf(stderr, "%s: Error - No such option: `%c'\n\n", PACKAGE, optopt);
print_help(1);
}
}
/* no remaining argumenst left ? read stdin() */
if((argc - optind) == 0) {
while((fgets(line, MAXLINE, stdin)) != NULL) {
/* strip newlines */
if(line[strlen(line) - 1] == '\n')
line[strlen(line) - 1] = '\0';
count++;
if(is_float(line) == 0)
num = atof(line);
else
num = atoi(line);
if(count == 1) highest = num, lowest = num;
if(num > highest) highest = num;
if(num < lowest) lowest = num;
total += num;
}
} else {
/* parse given elements as options */
/* just double the code .. ;-) */
for(; optind < argc; optind++) {
count++;
if(is_float(line) == 0)
num = atoi(argv[optind]);
else
num = atof(argv[optind]);
if(count == 1) highest = num, lowest = num;
if(num > highest) highest = num;
if(num < lowest) lowest = num;
total += num;
}
}
if(overview_flag == 1) {
printf("Nr of elements : %d\n", count);
printf("Sum of elements : %.2f\n", total);
printf("Average element : %.2f\n", (total / count));
printf("highest element : %.2f\n", highest);
printf("lowest element : %.2f\n", lowest);
} else
printf("%.2f\n", (total / count));
return 0;
}
/* returns -1 on error, 1 on `no dot', 0 on `dot' */
int is_float(char *val) {
int retval = -1;
if(strchr(val, '.') == NULL)
retval = 1;
else
retval = 0;
return retval;
}
/* status epilepticus, print help and exit with exval */
void print_help(int exval) {
printf("%s,%s mathiCheesEcal `eta' function\n", PACKAGE, VERSION);
printf("Usage: %s [-h] [-v] [-e] [[NUM1 NUM2 NUM3...]]\n\n", PACKAGE);
printf(" -h print this help and exit\n");
printf(" -v print version and exit\n");
printf(" -e print a more complete overview of parsed input\n\n");
exit(exval);
}
/* print program version and exit with exval */
void print_version(int exval) {
exit(exval);
}
The if-else statement is used to perform two operations for a single condition. The if-else statement is an extension to the if statement using which, we can perform two different operations, i.e., one is for the correctness of that condition, and the other is for the incorrectness of the condition. Here, we must notice that if and else block cannot be executed simiulteneously. Using if-else statement is always preferable since it always invokes an otherwise case with every if condition.
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Get string from stdin. Reads characters from the standard input (stdin) and stores them as a C string into str until a newline character or the end-of-file is reached. The newline character, if found, is not copied into str. A terminating null character is automatically appended after the characters copied to str. Notice that gets is quite different from fgets: not only gets uses stdin as source, but it does not include the ending newline character in the resulting string and does not allow to specify a maximum size for str (which can lead to buffer overflows).
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