-
Notifications
You must be signed in to change notification settings - Fork 0
/
Implications.c
118 lines (94 loc) · 3.11 KB
/
Implications.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
/**
* The Implications program implements an application
* that returns the correct direction of the arrow for
* the given mathematical implication.
*
* Author: Akari-T
* Version: 1.0
* Since: 2019-09-14
* */
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include "ImplicationsStrings.h"
/**
* Returns the mathematical implication in arrow form.
* It takes in user input and prints the correct arrow form depending
* on the input string. If invalid, notifies users.
* Method is called recursively, until user inputs exit to stop program
* or terminates program by pressing ctrl+d.
*
* Side Effects: None.
* */
void whichWay(){
/*Buffer to store user input.*/
char userInput[BUFSIZ];
/*Pointer to find the new line character in buffer.*/
char * ptr_newline = 0;
/*To keep track of the index of the buffer.*/
int index = 0;
/*Prints message to the users.*/
printf( STR_NEWLINE );
printf( STR_NEWLINE );
printf( STR_EXPECTED_INPUT );
printf( EXIT_PROGRAM );
/*If ctrl-D is detected, print message and return.*/
if( fgets( userInput, BUFSIZ, stdin ) == NULL )
printf( STR_BYE );
return;
/*Find the newline character and replace it with a NULL character.*/
ptr_newline = strchr( userInput, CHAR_NEWLINE );
*ptr_newline = NULL_CHAR;
/*Convert all characters of user input to lower case.*/
while( userInput[index] != NULL_CHAR ){
userInput[index] = (char)tolower(userInput[index]);
index++;
}
/*If stirng equals to exit, return.*/
if( strcmp( userInput, STR_EXIT ) == 0 )
printf( STR_BYE );
return;
/*If there is no input, print message to users.*/
if( userInput[0] == NULL_CHAR )
fprintf( stderr, STR_NO_INPUT );
/*If string matches one of them, print corresponding arrow form.*/
else if( strcmp( userInput, STR_IFTHEN ) == 0)
printf( P_Q );
else if( strcmp( userInput, STR_IMPLIES ) == 0)
printf( P_Q );
else if( strcmp( userInput, STR_ONLYIF ) == 0)
printf( P_Q );
else if( strcmp( userInput, STR_SUFFICIENTFOR ) == 0)
printf( P_Q );
else if( strcmp( userInput, STR_IF ) == 0)
printf( Q_P );
else if( strcmp( userInput, STR_WHENEVER ) == 0)
printf( Q_P );
else if( strcmp( userInput, STR_NECESSARYFOR ) == 0)
printf( Q_P );
/*Otherwise, print message to users.*/
else
fprintf( stderr, STR_INVALID, userInput );
/*Print a newline char after corresponding message is printed.*/
printf( STR_NEWLINE );
/*Recursively call method to continue taking input.*/
whichWay();
/*Return.*/
return;
}
/**
* Prints the statement and delegates main manipulation to whichWay().
* The purpose is to allow users to start the program.
*
* Paramters:
* argc - the number of inputs by the user
* argv - an array of pointers pointing to the user inputs
*
* Side Effects: None
* */
int main( int argc, char * argv[] ){
/*Print initial message to users.*/
printf( STR_MESSAGE );
/*Delegate main program to whichWay.*/
whichWay();
}