issue with multifunction utility program in c. - c

Question

The following program is supposed to read from the command line( using argv[]) and execute either one of three functions:
right(decides whether or not a triangle is a right triangle based on the side length: by typing mu -r [sidea] [sideb] [sidec]
findtext:(finds the sequence of a string inside of a given file: (ie,"hello") and lists the line number where it found it.
count: (counts the number of tabs, words and backspaces).
Findtext.c is functioning as it should:
for example if i type ./mu -f [string] [file.txt]
it successfully list the file and the line number in the file in which it was found.
but when I run the same code with the -r(right) option it gives me the following segmentation fault:
Program name: ./mu
3
Segmentation fault (core dumped)
where am i going wrong in this code?
#include <stdio.h>
#include <stdlib.h>
//#include "count.h"
//#include "right.h"
//#include "findtext.h"
#define STAND_ALONE 1
void right(int, char **);
void count(int, char **);
void findtext(int, char **);
#ifdef STAND_ALONE
int main(int argc, char *argv[])
{
printf("\n");
printf("Can only use one option(-f, -c, -r) at once. sorry!\n");
printf("\n");
printf("Program name: %s\n", argv[0]);
while ((argc > 1) && (argv[1][0] == '-'))
{
switch (argv[1][1])
{
case 'f': // findtext.c
printf("%s\n",&argv[1][2]);
findtext(argc, argv);
break;
case 'r': // right.c
printf("%s\n",&argv[1][2]);
right(argc, argv);
break;
case 'c': // count.c
printf("%s\n",&argv[1][2]);
count(argc,argv);
break;
default:
printf("Wrong Argument: %s\n", argv[1]);
}
++argv;
--argc;
}
return (0);
}
#endif
void right(int argc, char *argv[]){
int a;
int b;
int c;
int largest;
int a2;
int b2;
int c2;
/*if(argc != 4){
printf("please enter 3 sides, only \n");
} */
a = atoi(argv[2]);
b = atoi(argv[3]);
c = atoi(argv[4]);
//printf("argv2:%s ",argv[2]);
if((a <= 0 )|| (b <= 0) || (c <= 0))
printf("Only positive values allowed\n"); exit(0);
a2 = (a*a);
b2 = (b*b);
c2 = (c*c);
if((c > a) && (c > b))
largest = c;
if((b > a) && (b > c))
largest = b;
if((a > b) && (a > c))
largest = a;
if(largest == a){
printf("HEy hey hey!");
if((b2 + c2) == a2){ printf("%s %s %s is a right triangle\n",argv[2],argv[3],argv[4]); }
else{printf("%s %s %s is not a right triangle\n",argv[3],argv[2],argv[4]);}
}
if(largest == b){
printf("HEy");
if((a2 + c2) == b2){ printf("%s %s %s is a right triangle\n",argv[2],argv[3],argv[4]); }
else{printf("%s %s %s is not a right triangle\n",argv[2],argv[3],argv[4]);}
}
if(largest == c){
printf("yo");
if((a2 + b2) == c2){ printf("%s %s %s is a right triangle\n",argv[2],argv[3],argv[4]); }
else{printf("%s %s %s is not a right triangle\n",argv[2],argv[3],argv[4]);}
}
} /* end method right() */
void findtext(int argc, char *argv[]){
FILE *fin;
char buffer[100];
int counter;
char *ptr = buffer;
char *result;
//if(argc != 3) {printf("Usage: %s filename argc:%d\n", argv[0], argc); exit(1);}
fin = fopen(argv[3], "r");
if(!fin) {printf("Unable to open %s\n", argv[2]); exit(1); }
counter = 0;
while (fgets(buffer, 99, fin)){
counter = counter + 1;
if(strstr(ptr,argv[2])){
printf("%d. %s", counter, ptr);
printf("\n");
}
}
fclose (fin);
}
void count(int argc, char **argv){
FILE *fin;
int lcounter = 0;
int count = 0;
char name[100];
char ch;
int word = 0;
int nchar = 0;
fin = fopen(argv[1],"r"); // open file
if(fin==0){
printf("Could not find specified file.\n");
exit(0);
}
while((ch = getc(fin)) != EOF)
{
nchar++;
if(ch == '\n')
lcounter++;
if(isspace(ch) || ch == '\t' || ch == '\n')
word++;
}
printf("number of characters: %d\n",nchar);
printf("Lines: %d\n",lcounter);
printf("words: %d\n",word);
printf("\n");
fclose(fin);
}

Answer 1

if((a <= 0 )|| (b <= 0) || (c <= 0))
printf("Only positive values allowed\n"); exit(0);
Beware to the if-block. You are not using braces. At this point of the right function the program will end, in any case.
Of course this is not the bug you are looking for but it offers a starting point: the bug must necessarily be before this point.
You may need to debug what goes on here:
a = atoi(argv[2]);
b = atoi(argv[3]);
c = atoi(argv[4]);

Answer 2

See #Domenico De Felice answer.
Add #include <string.h>, #include <ctype.h>
You are accessing chars in argv[1] without knowing it is long enough to have those characters. while ((argc > 1) && (argv[1][0] == '-')). printf("%s\n",&argv[1][2]); should print only a line feed as argv[1] is "-r".
in right(), you do c = atoi(argv[4]); without knowing 5 args exist.
please review the need for your interesting code ++argv; --argc;. I really don't think these are going to do what you may want.
I think you are crashing because you do not always put the numbers of arguments (command parameters) that your code hopes to read. Increase your validation of program parameters before using them.
5.

Answer 3

You are crashing because you are trying to increment argv which is an array variable, not a pointer. So you cannot do argv++;
as a good programming principle, (although it is optional) argc, and argv should NOT be touched; you should use point to them using other variables if you want to run through them.
There are many other uglinesses in the code that try to access pointers and addresses without actually confirming whether they are there.
However, to begin with argv is where you are seg-faulting.