My task is to compare some words and to find a character which is not used in both of them. Here is my code. But I'm getting a warning:
[Warning] passing argument 1 of 'ret' makes pointer from integer without a cast [enabled by default].
And when I'm trying to run it it says consolepauser.exe stopped working
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
char ret(char a[1][10],char b[3][10])
{
int i,j,p,t;
for (i=0;i<1;i++)
for (j=0;j<10;j++)
for (p=0;p<3;p++)
for (t=0;t<10;t++)
{
if (tolower(a[i][j]==tolower(b[p][t])))
{
p=3;
break;
}
if (p==2)
if (t==9) return tolower(a[i][j]) ;
}
return 'N';
}
int main(int argc, char *argv[]) {
char k[3][10]={"cHaOs","TOP","blAa"};
char b[1][10]={"SomeThIng"};
char q[1][10]={"HaPa"};
if (ret(b[1][10],k[3][10])='N') printf("No character") ;
else printf("%c",ret(b[1][10],k[3][10])) ;
return 0;
}
You should pass the parameters as:
if (ret(b, k) == 'N') printf("No character");
else printf("%c", ret(b, k));
[Warning] passing argument 1 of 'ret' makes pointer from integer without a cast
b[1][10] is a char, not a variable of type char [1][10], you should call ret() like this: ret(b, k). Others are similar.
Note: the valid indexes of char b[1][10]; are b[0][0], b[0][1], ..., b[0][9], the indexes in `b[1][10]1 are out-of-bounds, and will cause undefined behavior.
Here is a syntax fixed version of your code, you may want to compare it with your original code to find out other problems in it:
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
char ret(char a[1][10],char b[3][10])
{
int i,j,p,t,e,r;
for (i=0;i<1;i++)
for (j=0;j<10;j++)
for (p=0;p<3;p++)
for (t=0;t<10;t++)
{
if (tolower(a[i][j])==tolower(b[p][t]))
{
p=3;
break;
}
if (p==2)
if (t==9) return tolower(a[i][j]) ;
}
return 'N';
}
int main(int argc, char *argv[]) {
int i,j,p,t,e,r;
char a,h;
char k[3][10]={"cHaOs","TOP","blAa"};
char b[1][10]={"SomeThIng"};
char q[1][10]={"HaPa"};
if (ret(b,k)=='N') printf("No character");
else printf("%c",ret(b,k));
return 0;
}
Related
I am writing some C in which the program is going to convert the first command line argument into a int and check to see if it is an int. If it isnt a integer value it will then attempt to check to see whether the string begins with a '.' character or not. For some reason I am getting an undefined reference. How is this an undefined reference when it seems to be defined?
Here is the following code:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <ctype.h>
#include <string.h>
int startswith(char,char);
int main(int argc, char * argv[]) {
int forst;
srand(time(NULL));
int speed_delay = rand() % 20;
printf("The speed delay is:%i\n", speed_delay);
int first = atoi(argv[1]);
printf("First:%i\n", first);
if (first == 0) {
//this means text was inserted instead of a number
if (startswith(first, '.')) {
printf("string starts with a period !");
}
} else {
}
int startswith(const char * one,
const char * two) {
if (strncmp(one, two, strlen(two)) == 0) {
return 1;
}
return 0;
}
}
Your declaration and definition of startswith are incompatible.
The declaration has two parameters of type char, but the function actually has two parameters of type const char *.
You also defined startswith inside of main. Functions cannot be nested.
Because no function exists that matches the declaration, you have an undefined reference.
Fix your declaration to match the definition.
int startswith( const char *, const char *);
You're also not calling this function correctly. You pass in an int and a char. It should be called like this:
if(startswith(argv[1],"."))
Try replacing int startswith(char,char); with below
static inline const char *startwith(const char *s, const char *prefix)
{
size_t sz = prefix ? strlen(prefix) : 0;
if(s && sz && strncmp(s, prefix, sz) == 0){
return s+sz;
}
return NULL;
}
I'm new to C and I'm having a hard time understanding how to call methods with pointers. Currently this code should reverse a null-terminated string, but I get the errors
main.c:8:12: error: use of undeclared identifier 'sas'
char* N = sas;
^ main.c:10:10: warning: incompatible integer to pointer conversion passing 'char' to parameter of type
'char *'; remove * [-Wint-conversion]
reverse(*N);
^~ ./header.h:3:27: note: passing argument to parameter 'N' here EXTERN void reverse(char *N);
My actual code is this:
Main:
#include <stdio.h>
#include <stdlib.h>
#include "header.h"
int main(int argc, char *argv[])
{
char* N = sas;
reverse(*N);
}
reverse:
#include <stdio.h>
#include "header.h
#include <stdlib.h>
void reverse(char *str)
{
char* end = str;
char temp;
printf("this is *str: %c\n", *str);
if (str)
{
while (*end)
{
++end:
}
end--;
while (str < end)
{
temp = *str
*str++ = *end;
*end-- = temp;
}
}
}
header.h:
#define EXTERN extern
EXTERN void reverse(char *N)
thanks for the help and time!
int main(int argc, char *argv[])
{
char* N = "sas";
reverse(*N);
}
First you make N point to a string constant. Then you try to reverse what N points to. But since N points to a string constant, you're trying to reverse a string constant. By definition, constants cannot have their values changed.
First of all, there're many syntax errors within that piece of code:
'sas' what is that? your compiler thinks it's a variable but can't find any with that name. if you wanted to put a "sas" string, then:
char* N = "sas";
inconsistant brackets. More closing brackets than opening ones, and no opening bracket after declaring your function.
As I understand it, you are trying to reverse a string. This is just a slight modification of your code.
Full Source:
#include <stdio.h>
#include <stdlib.h>
void reverse(char *N);
int main(int argc, char *argv[])
{
char strSas[] = "sas";
reverse(strSas);
}
void reverse(char *str)
{
char* end = str;
char temp;
if(str) {
printf("this is *str: %c\n", *str);
while(*end) {
++end;
}
end--;
while(str < end) {
temp = *str;
*str = *end;
*end = temp;
++str;
--end;
}
}
}
I'm trying to write a program that takes a string as a command line argument and then runs said argument through a function (str_to_int) that takes a string as an input. However, when I try to compile the program, I get a warning saying
initializing 'char *' with an expression of type 'int' [-Wint
conversion]
char* str = atoi(argv[1]);
^ ~~~~~~~~~~~~~
And when I run the program I get a segmentation fault
I've tested the str_to_int a lot so I'm pretty sure that the issue lies with the command line program. Here's the code for it.
#include "hw3.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(int argc, char *argv[])
{
char* str = atoi(argv[1]);
printf("%d\n", str_to_int(str));
return 0;
}
Can anyone tell me what I'm doing wrong? Thanks.
This is all you need, though it will crash if you leave out the command-line argument.
{
printf("%d\n", str_to_int(argv[1]));
return 0;
}
This is more robust:
int main(int argc, char *argv[])
{
if (argc == 1)
printf("missing parameter.");
else
printf("%d\n", str_to_int(argv[1]));
return 0;
}
#include "hw3.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(int argc, char *argv[])
{
char* str = argv[1];
printf("%d\n", str_to_int(str));
return 0;
}
just remove atoi function invocation and it should work
This procedure should convert a string that contains a set of double numbers separated by comma (e.g. 7.2,9.5,-5.515) to a vector of double type.
void ToDoubleVec(int d,const char* commaSeparated,double *result)
{
int i;
result[0]=atof(strtok(commaSeparated,","));
for(i=1;i<d;i++)
result[i]=atof(strtok(NULL,","));
}
Here is the snippet of program that calls it:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main(int argc,char** argv)
{
...
int i,dim=atoi(argv[1]);
double *lower;
lower = malloc(dim*sizeof(double));
ToDoubleVec(dim,argv[2],lower);
...
}
Debugger's output:
40 lower = malloc(dim*sizeof(double));
(gdb) s
42 ToDoubleVec(dim,argv[2],lower);
(gdb) s
ToDoubleVec (d=2, commaSeparated=0x7fffffffe9d3 "2.3,-62.1", result=0x603010) at testPSO.c:11
11 result[0]=atof(strtok(commaSeparated,","));
(gdb) s
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff77f56bb in ?? () from /lib/x86_64-linux-gnu/libc.so.6
Why doesn't it work? I was sure that I've allocated enough memory for the array and also parameters seems to be passed correctly.
You can reduce your code to this SSCCE (Short, Self-Contained, Correct Example), which crashes nicely when you leave out #include <string.h> and does not compile cleanly when you add #include <string.h>:
segv.c: In function ‘ToDoubleVec’:
segv.c:8:5: warning: implicit declaration of function ‘strtok’ [-Wimplicit-function-declaration]
segv.c:8:20: warning: initialization makes pointer from integer without a cast [enabled by default]
segv.c:14:20: warning: assignment makes pointer from integer without a cast [enabled by default]
Code:
#include <stdlib.h>
//#include <string.h>
static void ToDoubleVec(int d, const char* commaSeparated, double *result)
{
int i;
result[0] = atof(strtok(commaSeparated, ","));
for (i = 1; i < d; i++)
result[i] = atof(strtok(NULL, ","));
}
int main(void)
{
int dim = 2;
double *lower = malloc(dim*sizeof(double));
char arg[] = "7.2,9.5,-5.515";
ToDoubleVec(dim, arg, lower);
}
Passing the return value from a function such as strtok() which can return a null pointer directly to a function such as atof() which does not tolerate null pointers is foolhardy; it leads to crashes. If everything is correct, you'll be OK; if not, you'll crash and burn.
The unchecked memory allocation is a similar problem; you didn't even check that dim was non-zero (and non-negative) before doing the memory allocation in the original.
#include <assert.h>
#include <string.h>
#include <stdlib.h>
static void ToDoubleVec(int d, char *commaSeparated, double *result)
{
int i;
char *number = strtok(commaSeparated, ",");
if (number != 0)
{
result[0] = atof(number);
for (i = 1; i < d; i++)
{
number = strtok(NULL, ",");
if (number != 0)
result[i] = atof(number);
}
}
}
int main(void)
{
int dim = 2;
double *lower = malloc(dim*sizeof(double));
char arg[] = "7.2,9.5,-5.515";
assert(lower != 0);
ToDoubleVec(dim, arg, lower);
}
You could — and in one version of the code I did — add error printing to report if the tests on number failed. But the crash is caused by the implicit declaration of strtok() as returning int and not char *.
I have tried to compile your code, and the compiler warned me that strtok() takes as input a char* and not a const char*. Then I have tried this code, and it is working correctly:
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
void ToDoubleVec(int d, char* commaSeparated,double *result);
int main(int argc,char** argv)
{
int i,dim=atoi(argv[1]);
double *lower;
lower = malloc(dim*sizeof(double));
ToDoubleVec(dim,argv[2],lower);
for (i=0; i<dim; ++i) {
printf("%f\n", lower[i]);
}
return 0;
}
void ToDoubleVec(int d, char* commaSeparated,double *result)
{
int i;
result[0]=atof(strtok(commaSeparated,","));
for(i=1;i<d;i++)
result[i]=atof(strtok(NULL,","));
}
So try to change const char* to char*, and check the input you pass to your program, maybe it is not correct and this could be the problem.
I'm a beginner in C language. After reading the initial chapters of Ritchie's book, I wrote a program to generate random numbers and alphabets.
The program compiles fine with gcc. However on running it, it gives an error "Segmentation fault", which is incomprehensible to my limited knowledge. I'd be glad to understand what I've written wrong.
#include <stdio.h>
#include <stdlib.h>
#include "conio.h"
#include <time.h>
long int genrandom(int,int);
void randAlph(void);
char letterize(int);
int main (void) {
// char full[9];
// char part_non[4];
srand(time(0));
int i;
for (i=0;i<50;++i) {
randAlph();
};
}
long int genrandom(int mino,int maxo) {
int val=mino+rand()/(RAND_MAX/(maxo-mino)+1);
return val;
}
void randAlph (){
int val;
char text;
val=genrandom(0,26);
// return val;
text=letterize(val);
printf("%s ,",text);
}
char letterize(int num) {
char letter='A'+num;
return letter;
}
printf("%s ,",text); is wrong - it says that text is a nul-terminated array of chars. Use
printf("%c ,", text);
instead to print your single char.
#include <stdio.h>
#include <stdlib.h>
#include "conio.h"
#include <time.h>
int genrandom(int,int);
void randAlph(void);
char letterize(int);
int main (void) {
// char full[9];
// char part_non[4];
srand(time(0));
int i;
for (i=0;i<50;++i) {
randAlph();
};
}
int genrandom(int mino,int maxo) {//changed function return type to int
int val=mino+rand()/(RAND_MAX/(maxo-mino)+1); //Be careful when you are using '/' operator with integers
return val; //returning int here why set return type to long int?
}
void randAlph (){
int val;
char text;
val=genrandom(0,26);
// return val;
text=letterize(val);
printf("%c ,",text);//Replace %s with %c
}
char letterize(int num) { //No bound checking on num eh?
char letter='A'+num;
return letter;
}
That's all I had to say. :)
Why use %s when text is char. You dont need a string type in the function. Just a char would do. Change in the function : void randAlph ()
printf("%s ,",text);
to
printf("%c ,", text);