This question already has answers here:
strcmp on a line read with fgets
(6 answers)
Closed 7 years ago.
#include <stdio.h>
#include <math.h>
#include <string.h>
#define size 7
int computeN(char s1[])
{
int n=-1;
if(strcmp(s1, "black") == 0)
{
n = 0;
}
else if (strcmp(s1, "brown") == 0)
{
n = 10;
}
else if (strcmp(s1, "red") == 0)
{
n = 20;
}
else if (strcmp(s1, "orange") == 0)
{
n = 30;
}
else if (strcmp(s1, "yellow") == 0)
{
n = 40;
}
else if (strcmp(s1, "green") == 0)
{
n = 50;
}
else if (strcmp(s1, "blue") == 0)
{
n = 60;
}
else if (strcmp(s1, "violet") == 0)
{
n = 70;
}
else if (strcmp(s1, "grey") == 0)
{
n = 80;
}
else if (strcmp(s1, "white") == 0)
{
n = 90;
}
printf("%d\n", n);
return n;
}
int computeN2(char s2[])
{
int n1=-1;
if(strcmp(s2, "black") == 0)
{
n1 = 0;
}
else if (strcmp(s2, "brown") == 0)
{
n1 = 1;
}
else if (strcmp(s2, "red") == 0)
{
n1 = 2;
}
else if (strcmp(s2, "orange") == 0)
{
n1= 3;
}
else if (strcmp(s2, "yellow") == 0)
{
n1 = 4;
}
else if (strcmp(s2, "green") == 0)
{
n1 = 5;
}
else if (strcmp(s2, "blue") == 0)
{
n1 = 6;
}
else if (strcmp(s2, "violet") == 0)
{
n1 = 7;
}
else if (strcmp(s2, "grey") == 0)
{
n1 = 8;
}
else if (strcmp(s2, "white") == 0)
{
n1 = 9;
}
printf("%d\n", n1);
return n1;
}
int computeExponent(char s3[])
{
int exp=0;
if(strcmp(s3, "black") == 0)
{
exp = 1;
}
else if (strcmp(s3, "brown") == 0)
{
exp = 10;
}
else if (strcmp(s3, "red") == 0)
{
exp = 100;
}
else if (strcmp(s3, "orange") == 0)
{
exp = 1000;
}
else if (strcmp(s3, "yellow") == 0)
{
exp = 10000;
}
else if (strcmp(s3, "green") == 0)
{
exp = 100000;
}
else if (strcmp(s3, "blue") == 0)
{
exp = 1000000;
}
else if (strcmp(s3, "violet") == 0)
{
exp = 10000000;
}
else if (strcmp(s3, "gray") == 0)
{
exp = 100000000;
}
else if (strcmp(s3, "white") == 0)
{
exp = 1000000000;
}
printf("%d\n", exp);
return exp;
}
int computeResistance(int x, int y, int z)
{
int omega = ((x+y) * z);
return omega;
}
int main(void)
{
char color_codes[10][7] = {"black","brown","red","orange","yellow","green","blue","violet","gray","white"};
char s1[7], s2[7], s3[7];
int n, n1, choice;
printf("Enter the colors of the resistor's three bands, beginning with\n");
printf("the band nearest the end. Type the colors in lowercase letters\n");
printf("only, NO CAPS\n");
printf("Band 1 =>\n"); //prints prompts for bands
fgets(s1, size, stdin); //stores band 1 in s1
printf("Band 2 => \n"); //prints prompt
fgets(s2, size, stdin); //stores band 2 in s2
printf("Band 3 => \n"); //prints prompt
fgets(s3, size, stdin); //stores band 3 in s3
printf("Resistance value: %d\n", computeResistance(computeN(s1), computeN2(s2), computeExponent(s3))); //computes resistance
return (0); //make the exit
}
The strings are being stored properly; the issue is the fact that within the functions the correct value is not being found within the comparison in order to find the resistance with the algorithm. If the user enters 'red', 'red', 'red', the values n,n1, and exp will be equal to -1,-1,0. What could be causing this?
The problem here is, fgets() scans and stores the trailing newline, too, into the input buffer.
You need to get rid of that newline before sending the input for comparison. Otherwise, your string comparison is pretty much likely to fail.
A very simple solution can be like, check the string length of the input, then check on the last index value against the newline (\n), if you found that, replace that with null (\0) and then, pass on the input to the comparison function(s).
fgets includes the newline character in the string it reads. You'll either have to remove it or use a function like scanf which does not include the newline. (If you use scanf, remember to use e.g. %7s specifiers to prevent buffer overflows).
Related
I'm super new in C, trying to solve CS50's credit problem here.
So I wrote a function, that should check some parameters, and return a string, which I use in the main function to print an answer.
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <math.h>
int lunh(long n);
char* check(long nu);
int main(void)
{
long number = get_long("Number: ");
printf("%s", check(number));
}
int lunh(long n)
{
int length, step_one, num;
long tens;
step_one = 0;
length = floor(log10(labs(n))) + 1;
for (int i = length, powering = 1; i > length / 2; i--)
{
tens = pow(10, powering);
num = ((n / tens) % 10) * 2;
if (floor(log10(abs(num))) + 1 > 1)
{
while (num)
{
step_one += num % 10;
num /= 10;
}
step_one += num;
powering += 2;
}
else
{
step_one += num;
powering += 2;
}
}
for (int i = length, powering = 0; i > length / 2; i--)
{
tens = pow(10, powering);
num = ((n / tens) % 10);
step_one += num;
powering += 2;
}
if (step_one % 10 == 0)
{
return 1;
}
else
{
return 0;
}
}
char* check(long nu)
{
int l, first_two_digits, first_one;
l = floor(log10(labs(nu))) + 1;
first_one = nu / 1000;
first_two_digits = nu / 100;
char* answer = NULL;
if (l == 15)
{
if (first_two_digits == 34 || first_two_digits == 37)
{
if (lunh(nu) == 1)
{
answer = "AMEX";
}
else
{
answer = "INVALID";
}
}
}
else if (l == 13 || first_one == 4)
{
if (lunh(nu) == 1)
{
answer = "VISA";
}
else
{
answer = "INVALID";
}
}
else if (l == 16)
{
if (first_two_digits == 51 || first_two_digits == 52 || first_two_digits == 53 || first_two_digits == 54 || first_two_digits == 55)
{
if (lunh(nu) == 1)
{
answer = "MASTERCARD";
}
else
{
answer = "INVALID";
}
}
}
else
{
answer = "INVALID";
}
printf("%s", answer);
return answer;
}
Input: 4003600000000014
Expected output: "VISA"
Current output: nothing, after inputting the number, the program stops.
At least one problem is here: else if (l == 13 || first_one == 4). From the spec:
Visa uses 13- and 16-digit numbers.
Visa numbers all start with 4
That if test will produce VISA if length is 13 or card starts with 4. The sample input is a 16 digit number.
I am trying to build a program that could add up binary numbers, of arbitrary length, separated by a whitespace. I don't want to be limited by a maximum number length, therefore I'm doing everything without built-in number types, only chars. I read the numbers from a file. I perform everything on stack.
I can't loop the part where I read and add numbers. My guess is that it's because I can't find a way to distinguish new line from EOF. The program works this way: I read first number and save it into first stack, then I read second number and save in second stack. Then I add it up, save into third stack and transfer it to first stack. I read next number, save it into second stack, add up and so on. So I basically want to loop the second reading and summing. Here is the source code part:
while( !isspace(c=(char)getc(ifp))) {
if( c == '0' || c == '1'){
if(!push(&a , c)){
clearStack(&a);
printf("alloc error");
return 0;
}
}else{
clearStack(&a);
printf("error1");
return 0;
}
}
if( a.size == 0 ){
printf("error2");
return 0;
}
while (!feof(ifp)) {
while( !isspace(c=(char)getc(ifp))) {
if( c == '0' || c == '1'){
if(!push(&b , c)){
clearStack(&a);
clearStack(&b);
printf("alloc error");
return 0;
}
}
else{
//clearStack(&a);
//clearStack(&b);
printf("error3");
//return 0;
}
}
if( b.size == 0 ){
if (a.size == 0){
printf("error4");
}
}
topA = a.size;
topB = b.size;
carry = 0;
while( topA > 0 || topB > 0) {
if ( ( topA > 0 ) ){
topA--;
if(a.data[topA] == '1'){
x = 1;
}else{
x = 0;
}
}else{
x = 0;
}
if ( ( topB > 0 ) ){
topB--;
if(b.data[topB] == '1'){
y = 1;
}else{
y = 0;
}
}else{
y = 0;
}
sum = x + y + carry;
if (sum == 2 || sum == 3){
carry = 1;
}else{
carry = 0;
}
if (sum == 1 || sum == 3) {
c = '1';
}else{
c = '0';
}
if(!push(&output , c)){
clearStack(&a);
clearStack(&b);
clearStack(&output);
printf("alloc error");
return 0;
}
}
if (carry == 1) {
if(!push(&output , '1')){
clearStack(&a);
clearStack(&b);
clearStack(&output);
printf("alloc error");
return 0;
}
}
clearStack(&a);
for (i=0; i < output.size; i++){
push(&a , output.data[i]);
}
clearStack(&b);
clearStack(&output);
} /*end of EOF while*/
For some reason, although it reads multiple times, it reads wrong and works only for 2 numbers. The file looks like this: "1 1", but when its "1 1 1" it will just add first 2 numbers. I don't know where am I making a mistake. Below I attach the whole source code. I invoke the program in console like this: ./program file. I know that the case is poorly described but can't do it in a better manner, I will add comments if anything is needed.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
struct stack {
char *data;
int size;
};
int push(struct stack * s, char c){
char * newData = (char *)realloc( s->data , (s->size + 1) * sizeof(char));
if( newData ){
s->data = newData;
s->data[s->size]=c;
s->size++;
return 1;
}else{
return 0;
}
}
/* not needed */
char pop(struct stack * s){
if(s->size > 0){
char result = s->data[s->size-1];
char * newData = (char *)realloc( s->data , s->size - 1);
if( newData ){
s->data = newData;
s->size--;
return result;
}else{
return 0;
}
}
else{
return 0;
}
}
struct stack newStack(){
struct stack s;
s.data = NULL;
s.size = 0;
return s;
}
void clearStack(struct stack * s){
free(s->data);
s->data = NULL;
s->size = 0;
}
int main (int argc, char const * argv[])
{
struct stack a = newStack();
struct stack b = newStack();
int topA, topB, x , y, carry, sum,i , start;
struct stack output = newStack();
char c;
FILE *ifp;
if(argc!=2){printf("Usage: ./a.out input_file."); return(1);}
if(!(ifp = fopen(argv[1], "r"))){printf("Unable to open input file!"); return(2);}
while( !isspace(c=(char)getc(ifp))) {
if( c == '0' || c == '1'){
if(!push(&a , c)){
clearStack(&a);
printf("alloc error");
return 0;
}
}else{
clearStack(&a);
printf("error1");
return 0;
}
}
if( a.size == 0 ){
printf("error2");
return 0;
}
while (!feof(ifp)) {
while( !isspace(c=(char)getc(ifp))) {
if( c == '0' || c == '1'){
if(!push(&b , c)){
clearStack(&a);
clearStack(&b);
printf("alloc error");
return 0;
}
}
else if (c == '\0' || c == ' ' || c == '\n'){
}
else{
//clearStack(&a);
//clearStack(&b);
printf("error3");
//return 0;
}
}
if( b.size == 0 ){
if (a.size == 0){
printf("error4");
//return 0;
}
}
topA = a.size;
topB = b.size;
carry = 0;
while( topA > 0 || topB > 0) {
if ( ( topA > 0 ) ){
topA--;
if(a.data[topA] == '1'){
x = 1;
}else{
x = 0;
}
}else{
x = 0;
}
if ( ( topB > 0 ) ){
topB--;
if(b.data[topB] == '1'){
y = 1;
}else{
y = 0;
}
}else{
y = 0;
}
sum = x + y + carry;
if (sum == 2 || sum == 3){
carry = 1;
}else{
carry = 0;
}
if (sum == 1 || sum == 3) {
c = '1';
}else{
c = '0';
}
if(!push(&output , c)){
clearStack(&a);
clearStack(&b);
clearStack(&output);
printf("alloc error");
return 0;
}
}
if (carry == 1) {
if(!push(&output , '1')){
clearStack(&a);
clearStack(&b);
clearStack(&output);
printf("alloc error");
return 0;
}
}
clearStack(&a);
for (i=0; i < output.size; i++){
push(&a , output.data[i]);
}
clearStack(&b);
clearStack(&output);
} /*end of EOF while*/
for (i=a.size - 1; i >= 0; i--){
if(a.data[i] == '1' || start){
start=1;
printf("%c", a.data[i]);
}
}
printf("\n");
clearStack(&a);
//clearStack(&b);
//clearStack(&output);
return 0;
}
Trying to implement a very simple Roman Numeral to Decimal converter but can't seem to figure out a way for the program to return -1 if any non-roman numeral characters are in the string. This is what I have so far.
#include <stdio.h>
#include <ctype.h>
int convertFromRoman(const char *s)
{
int i = 0;
int total = 0;
while (s[i] != '\0') {
if (isalpha(s[i]) == 0) {
return -1;
}
if (toupper(s[i]) == 'I') {
total += 1;
}
if (toupper(s[i]) == 'V') {
total += 5;
}
if (toupper(s[i]) == 'X') {
total += 10;
}
if (toupper(s[i]) == 'L') {
total += 50;
}
if (toupper(s[i]) == 'C') {
total += 100;
}
if (toupper(s[i]) == 'D') {
total += 500;
}
if (toupper(s[i]) == 'M') {
total += 1000;
} else {
return -1;
}
i++;
}
if (total == 0) {
return -1;
}
return total;
}
int main()
{
printf("%d\n", convertFromRoman("XVII"));
printf("%d\n", convertFromRoman("ABC"));
}
The first one should return 17 and the second one should return -1. However they both return -1 but if I remove the else statement, the first one returns 17 and the second one returns 100.
Any help is appreciated.
Change if() if() if() else to if() else if () else if() else
if (toupper(s[i]) == 'I') {
total += 1;
}
else if (toupper(s[i]) == 'V') {
total += 5;
}
else if (toupper(s[i]) == 'X') {
total += 10;
}
....
else if (toupper(s[i]) == 'M') {
total += 1000;
} else {
return -1;
}
Not really an answer, just a bit of fun/alternate way of looking at the problem. It does solve the problem if you're not considering ordering just adding "digit" values.
char *romanNumerals = "IVXLCDM";
int values[] = { 1, 5, 10, 50, 100, 500, 1000 };
int convertFromRoman(const char *s) {
int val = 0;
for (int i = 0; s[i]; i++) {
char *idx;
if (NULL == (idx = strchr(romanNumerals, toupper(s[i])))) {
return -1;
}
val += values[idx - romanNumerals];
}
return val;
}
The program is supposed to read in digits one after the other to see if they are consecutive numbers or not. The second digit seems to be scanning as 21 all the time for some reason. Could anyone show me where i am going wrong? Thanks.
#include<stdio.h>
#include<stdlib.h>
int main()
{
int a=1, e=1,n, digit1, compared;
char y, z;
scanf("n=%d, digits=%c%c", &n, &y, &z);
digit1 = atoi(&y);
compared = atoi(&z);
if(digit1 == 0)
{
printf("False");
}
else if(compared == (digit1 + 1))
{
digit1++;
for(a = 1;a < (n - 1);a++)
{
scanf("%c", &z);
compared = atoi(&z);
if(compared == digit1 + 1)
{
e++;
digit1++;
}
}
if(e == (n - 1))
{
printf("True\n");
}
else
{
printf("False");
}
}
else if(compared == (digit1 - 1))
{
digit1--;
for(a = 1;a < (n - 1);a++)
{
scanf("%c", &z);
compared = atoi(&z);
if(compared == (digit1 - 1))
{
e++;
digit1--;
}
}
if(e == (n - 1))
{
printf("True\n");
}
else
{
printf("False");
}
}
return 0;
}
So, essentially I have two files:
File 1:
//
// main.c
// frederickterry
//
// Created by Rick Terry on 1/15/15.
// Copyright (c) 2015 Rick Terry. All rights reserved.
//
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int size (char *g) {
int ofs = 0;
while (*(g+ofs) != '\0') {
++ofs;
}
return ofs;
}
int parse(char *g) {
// Setup
char binaryConnective;
int negated = 0;
// Looking for propositions
int fmlaLength = size(g);
if(fmlaLength == 0) {
return 1;
}
if(fmlaLength == 1) {
if(g[0] == 'p') {
return 1;
} else if (g[0] == 'q') {
return 1;
} else if (g[0] == 'r') {
return 1;
} else {
return 0;
}
}
// Now looking for negated preposition
if(fmlaLength == 2) {
char temp[100];
strcpy(temp, g);
if(g[0] == '-') {
negated = 1;
int negatedprop = parse(g+1);
if(negatedprop == 1) {
return 2;
}
}
}
// Checking if Binary Formula
char arrayleft[50];
char arrayright[50];
char *left = "";
char *right = "";
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int binarypresent = 0;
if(fmlaLength != 1 && fmlaLength != 2) {
if(g[0] == '-') {
int negatedBinary = parse(g+1);
if(negatedBinary == 1 || negatedBinary == 2 || negatedBinary == 3) {
return 2;
} else {
return 0;
}
}
int i = 0;
int l = 0;
int p = strlen(g);
for(l = 0; l < strlen(g)/2; l++) {
if(g[l] == '(' && g[p-l-1] == ')') {
i++;
}
}
for(int q = i; q < strlen(g); q++) {
if(g[q] == '(') {
numLeft++;
} else if(g[q] == ')') {
numRight++;
}
arrayleft[q] = g[q];
//printf("%c", arrayleft[i]);
//printf("%s", left);
if((numRight == numLeft) && (g[q+1] == 'v' || g[q+1] == '>' || g[q+1] == '^')) {
arrayleft[q+1] = '\0';
bclocation = q+1;
binaryConnective = g[q+1];
binarypresent = 1;
// printf("The binary connecive is: %c\n", binaryConnective);
break;
}
}
if(binarypresent == 0) {
return 0;
}
int j = 0;
for(int i = bclocation+1; i < strlen(g)-1; i++) {
arrayright[j] = g[i];
j++;
}
arrayright[j] = '\0';
left = &arrayleft[1];
right = &arrayright[0];
//printf("Printed a second time, fmla 1 is: %s", left);
int parseleft = parse(left);
// printf("Parse left result: %d\n", parseleft);
if(parseleft == 0) {
return 0;
}
int parseright = parse(right);
if(parseright == 0) {
return 0;
}
// printf("Parse right result: %d\n", parseleft);
if(negated == 1) {
return 2;
} else {
return 3;
}
}
return 0;
}
int type(char *g) {
if(parse(g) == 1 ||parse(g) == 2 || parse(g) == 3) {
if(parse(g) == 1) {
return 1;
}
/* Literals, Positive and Negative */
if(parse(g) == 2 && size(g) == 2) {
return 1;
}
/* Double Negations */
if(g[0] == '-' && g[1] == '-') {
return 4;
}
/* Alpha & Beta Formulas */
char binaryConnective;
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int binarypresent = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
bclocation = i+1;
binaryConnective = g[i+1];
binarypresent = 1;
break;
}
}
}
/* Connective established */
if(binaryConnective == '^') {
if(g[0] == '-') {
return 3;
} else {
return 2;
}
} else if(binaryConnective == '>') {
if(g[0] == '-') {
return 2;
} else {
return 3;
}
} else if (binaryConnective == 'v') {
if(g[0] == '-') {
return 2;
} else {
return 3;
}
}
}
return 0;
}
char bin(char *g) {
char binaryConnective;
char arrayLeft[50];
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
int j = 0;
arrayLeft[j++] = g[i];
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
arrayLeft[i+1] = '\0';
bclocation = i+1;
binaryConnective = g[i+1];
return binaryConnective;
}
}
}
return binaryConnective;
}
char *partone(char *g) {
char binaryConnective;
char arrayLeft[50];
char arrayRight[50];
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
int j = 0;
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
arrayLeft[j] = g[i];
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
arrayLeft[j+1] = '\0';
bclocation = i+1;
binaryConnective = g[i+1];
break;
}
}
j++;
}
int m = 0;
for(int k = bclocation+1; k < strlen(g)-1; k++) {
arrayRight[m] = g[k];
m++;
}
arrayRight[m] = '\0';
char* leftSide = &arrayLeft[0];
// printf("%s\n", leftSide);
// printf("%s\n", rightSide);
int k = 0;
k++;
return leftSide;
}
char *parttwo(char *g) {
char binaryConnective;
char arrayLeft[50];
char arrayRight[50];
int numLeft = 0;
int numRight = 0;
int bclocation = 0;
int i = 0;
if(g[0] == '(') {
i++;
}
if(g[0] == '-') {
i++;
if(g[1] == '(') {
i++;
}
}
int j = 0;
for(i; i < strlen(g); ++i) {
if(g[i] == '(') {
numLeft++;
} else if(g[i] == ')') {
numRight++;
}
arrayLeft[j] = g[i];
if(numRight == numLeft) {
if(g[i+1] == 'v' || g[i+1] == '>' || g[i+1] == '^') {
arrayLeft[j+1] = '\0';
bclocation = i+1;
binaryConnective = g[i+1];
break;
}
}
j++;
}
int m = 0;
int n = size(g) - 1;
if(g[strlen(g)-1] != ')') {
n++;
}
for(int k = bclocation+1; k < n; k++) {
arrayRight[m] = g[k];
m++;
}
arrayRight[m] = '\0';
char* leftSide = &arrayLeft[0];
char* rightSide = &arrayRight[0];
// printf("%s\n", leftSide);
// printf("%s\n", rightSide);
return rightSide;
}
char *firstexp(char *g) {
char* left = partone(g);
char leftArray[50];
int i = 0;
for(i; i < strlen(left); i++) {
leftArray[i] = left[i];
}
leftArray[i] = '\0';
char binConnective = bin(g);
int typeG = type(g);
if(typeG == 2) {
if(binConnective == '^') {
return &leftArray;
} else if(binConnective == '>') {
return &leftArray;
}
} else if(typeG == 3) {
if(binConnective == 'v')
return &leftArray;
}
char temp[50];
for(int i = 0; i < strlen(leftArray); i++) {
temp[i+1] = leftArray[i];
}
temp[0] = '-';
char* lefttwo = &temp[0];
if(typeG == 2) {
if(binConnective == 'v') {
return lefttwo;
}
} else if(typeG == 3) {
if(binConnective == '>' || binConnective == '^') {
return lefttwo;
}
}
return "Hello";
}
char *secondexp(char *g) {
// char binaryConnective = bin(g);
// char* right = parttwo(g);
// char rightArray[50];
// int i = 0;
// for(i; i< strlen(right); i++) {
// rightArray[i+1] = right[i];
// }
// rightArray[i] = '\0';
// int typeG = type(g);
// if(type(g) == 2) {
// if(binaryConnective == '^') {
// return &rightArray;
// }
// } else if(type(g) == 3) {
// if(binaryConnective == 'v' || binaryConnective == '>') {
// return &rightArray;
// }
// }
return "Hello";
}
typedef struct tableau tableau;
\
\
struct tableau {
char *root;
tableau *left;
tableau *right;
tableau *parent;
int closedbranch;
};
int closed(tableau *t) {
return 0;
}
void complete(tableau *t) {
}
/*int main(int argc, const char * argv[])
{
printf("Hello, World!\n");
printf("%d \n", parse("p^q"));
printf("%d \n", type("p^q"));
printf("%c \n", bin("p^q"));
printf("%s\n", partone("p^q"));
printf("%s\n", parttwo("p^q"));
printf("%s\n", firstexp("p^q"));
printf("Simulation complete");
return 0;
}*/
File 2:
#include <stdio.h>
#include <string.h> /* for all the new-fangled string functions */
#include <stdlib.h> /* malloc, free, rand */
#include "yourfile.h"
int Fsize = 50;
int main()
{ /*input a string and check if its a propositional formula */
char *name = malloc(Fsize);
printf("Enter a formula:");
scanf("%s", name);
int p=parse(name);
switch(p)
{case(0): printf("not a formula");break;
case(1): printf("a proposition");break;
case(2): printf("a negated formula");break;
case(3): printf("a binary formula");break;
default: printf("what the f***!");
}
printf("\n");
if (p==3)
{
printf("the first part is %s and the second part is %s", partone(name), parttwo(name));
printf(" the binary connective is %c \n", bin(name));
}
int t =type(name);
switch(t)
{case(0):printf("I told you, not a formula");break;
case(1): printf("A literal");break;
case(2): printf("An alpha formula, ");break;
case(3): printf("A beta formula, ");break;
case(4): printf("Double negation");break;
default: printf("SOmewthing's wrong");
}
if(t==2) printf("first expansion fmla is %s, second expansion fmla is %s\n", firstexp(name), secondexp(name));
if(t==3) printf("first expansion fmla is %s, second expansion fmla is %s\n", firstexp(name), secondexp(name));
tableau tab;
tab.root = name;
tab.left=0;
tab.parent=0;
tab.right=0;
tab.closedbranch=0;
complete(&tab);/*expand the root node then recursively expand any child nodes */
if (closed(&tab)) printf("%s is not satisfiable", name);
else printf("%s is satisfiable", name);
return(0);
}
If you look at the first file, you'll see a method called * firstexp(char * g).
This method runs perfectly, but only if another method called * secondexp(char * g) is commented out.
If * secondexp(char * g) is commented out, then *firstexp runs like this:
Enter a formula:((pvq)>-p)
a binary formula
the first part is (pvq) and the second part is -p the binary connective is >
A beta formula, first expansion fmla is -(pvq), second expansion fmla is Hello
((pvq)>-p) is satisfiableProgram ended with exit code: 0
otherwise, if *secondexp is not commented out, it runs like this:
Enter a formula:((pvq)>-p)
a binary formula
the first part is (pvq) and the second part is -p the binary connective is >
A beta formula, first expansion fmla is \240L, second expansion fmla is (-
((pvq)>-p) is satisfiable. Program ended with exit code: 0
As you can see, the outputs are completely different despite the same input. Can someone explain what's going on here?
In the commented-out parts of secondexp and in parttwo, you return the address of a local variable, which you shouldn't do.
You seem to fill a lot of ad-hoc sized auxiliary arrays. These have the problem that they might overflow for larger expressions and also that you cannot return them unless you allocate them on the heap with malloc, which also means that you have to free them later.
At first glance, the strings you want to return are substrings or slices of the expression string. That means that the data for these strings is already there.
You could (safely) return pointers into that string. That is what, for example strchr and strstr do. If you are willing to modify the original string, you could also place null terminators '\0' after substrings. That's what strtok does, and it has the disadvantage that you lose the information at that place: If you string is a*b and you modify it to a\0b, you will not know which operator there was.
Another method is to create a struct that stores a slice as pointer into the string and a length:
struct slice {
const char *p;
int length;
};
You can then safely return slices of the original string without needing to worry about additional memory.
You can also use the standard functions in most cases, if you stick to the strn variants. When you print a slice, you can do so by specifying a field width in printf formats:
printf("Second part: '%.*s'\n", s->length, s->p);
In your parttwo() function you return the address of a local variable
return rightSide;
where rightSide is a pointer to a local variable.
It appears that your compiler gave you a warning about this which you solved by making a pointer to the local variabe arrayRight, that may confuse the compiler but the result will be the same, the data in arrayRight will no longer exist after the function returns.
You are doing the same all over your code, and even worse, in the secondexp() function you return a the address of a local variable taking it's address, you are not only returning the address to a local variabel, but also with a type that is not compatible with the return type of the function.
This is one of many probable issues that your code may have, but you need to start fixing that to continue with other possible problems.
Note: enable extra warnings when compiler and listen to them, don't try to fool the compiler unless you know exactly what you're doing.