Tail -c linux command implementation in C
0
I need to write a tail in C language, where the input stream will be the argument in the console. The function should cut n characters from the input data. The command calling the program should be "echo" an example text "| ./a.out 4" - that is, the last 4 characters of the given input will be printed.
Unfortunately, my function does not print anything to me.
Thanks in advance. If there are any other, smarter solutions then I am open to suggestions.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define BUFFSIZE 1024
#define MAXLINES 100
char* tailFunction (const char* argv)
char* buf, data;
int n = 0, i =0;
buf = malloc(sizeof(char) * MAXLINES);
n = atoi(argv[0]+1);
while (data != EOF)
data = getc(stdin);
buf[i] = data;
i++;
int x = strlen(buf) - n;
for ( ; x < strlen(buf) ; x++)
printf("%c", buf[x]);
free(buf);
return 0;
int main(int argc, const char *argv)
if (argc !=2)
return -1;
if (argv < MAXLINES)
tailFunction(argv);
return 0;
else return -1;
c buffer implementation tail
asked Nov 14 '18 at 18:05
SheeppSheepp
1
|
show 3 more comments
0
I need to write a tail in C language, where the input stream will be the argument in the console. The function should cut n characters from the input data. The command calling the program should be "echo" an example text "| ./a.out 4" - that is, the last 4 characters of the given input will be printed.
Unfortunately, my function does not print anything to me.
Thanks in advance. If there are any other, smarter solutions then I am open to suggestions.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define BUFFSIZE 1024
#define MAXLINES 100
char* tailFunction (const char* argv)
char* buf, data;
int n = 0, i =0;
buf = malloc(sizeof(char) * MAXLINES);
n = atoi(argv[0]+1);
while (data != EOF)
data = getc(stdin);
buf[i] = data;
i++;
int x = strlen(buf) - n;
for ( ; x < strlen(buf) ; x++)
printf("%c", buf[x]);
free(buf);
return 0;
int main(int argc, const char *argv)
if (argc !=2)
return -1;
if (argv < MAXLINES)
tailFunction(argv);
return 0;
else return -1;
c buffer implementation tail
asked Nov 14 '18 at 18:05
SheeppSheepp
1
You should try to compile in debug mode (-gon gcc,clang) with not optimizations (-O0on gcc,clang) and run you program using valgrind
– Gabriel Devillers
Nov 14 '18 at 18:10
You should start by enabling compiler warnings (-Wall -Wextra -Wpedanticon gcc or clang, also set the compiler to optimize-O3). If you can, enable-fsanitize=addressand other sanitizers, once the code compiles without warnings.
– EOF
Nov 14 '18 at 18:26
there is no memory allocation. I do not quite know why, if it's malloc.
– Sheepp
Nov 14 '18 at 18:37
@Sheepp How do you know there is no memory allocation?
– EOF
Nov 14 '18 at 18:49
@EOF From valgrind. There is an information about 0 allocs and 0 frees.
– Sheepp
Nov 14 '18 at 18:52
|
show 3 more comments
0
0
0
I need to write a tail in C language, where the input stream will be the argument in the console. The function should cut n characters from the input data. The command calling the program should be "echo" an example text "| ./a.out 4" - that is, the last 4 characters of the given input will be printed.
Unfortunately, my function does not print anything to me.
Thanks in advance. If there are any other, smarter solutions then I am open to suggestions.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define BUFFSIZE 1024
#define MAXLINES 100
char* tailFunction (const char* argv)
char* buf, data;
int n = 0, i =0;
buf = malloc(sizeof(char) * MAXLINES);
n = atoi(argv[0]+1);
while (data != EOF)
data = getc(stdin);
buf[i] = data;
i++;
int x = strlen(buf) - n;
for ( ; x < strlen(buf) ; x++)
printf("%c", buf[x]);
free(buf);
return 0;
int main(int argc, const char *argv)
if (argc !=2)
return -1;
if (argv < MAXLINES)
tailFunction(argv);
return 0;
else return -1;
c buffer implementation tail
asked Nov 14 '18 at 18:05
SheeppSheepp
1
I need to write a tail in C language, where the input stream will be the argument in the console. The function should cut n characters from the input data. The command calling the program should be "echo" an example text "| ./a.out 4" - that is, the last 4 characters of the given input will be printed.
Unfortunately, my function does not print anything to me.
Thanks in advance. If there are any other, smarter solutions then I am open to suggestions.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define BUFFSIZE 1024
#define MAXLINES 100
char* tailFunction (const char* argv)
char* buf, data;
int n = 0, i =0;
buf = malloc(sizeof(char) * MAXLINES);
n = atoi(argv[0]+1);
while (data != EOF)
data = getc(stdin);
buf[i] = data;
i++;
int x = strlen(buf) - n;
for ( ; x < strlen(buf) ; x++)
printf("%c", buf[x]);
free(buf);
return 0;
int main(int argc, const char *argv)
if (argc !=2)
return -1;
if (argv < MAXLINES)
tailFunction(argv);
return 0;
else return -1;
c buffer implementation tail
c buffer implementation tail
asked Nov 14 '18 at 18:05
SheeppSheepp
1
asked Nov 14 '18 at 18:05
SheeppSheepp
1
asked Nov 14 '18 at 18:05
SheeppSheepp
1
asked Nov 14 '18 at 18:05
SheeppSheepp
1
asked Nov 14 '18 at 18:05
SheeppSheepp
1
1
You should try to compile in debug mode (-gon gcc,clang) with not optimizations (-O0on gcc,clang) and run you program using valgrind
– Gabriel Devillers
Nov 14 '18 at 18:10
You should start by enabling compiler warnings (-Wall -Wextra -Wpedanticon gcc or clang, also set the compiler to optimize-O3). If you can, enable-fsanitize=addressand other sanitizers, once the code compiles without warnings.
– EOF
Nov 14 '18 at 18:26
there is no memory allocation. I do not quite know why, if it's malloc.
– Sheepp
Nov 14 '18 at 18:37
@Sheepp How do you know there is no memory allocation?
– EOF
Nov 14 '18 at 18:49
@EOF From valgrind. There is an information about 0 allocs and 0 frees.
– Sheepp
Nov 14 '18 at 18:52
|
show 3 more comments
You should try to compile in debug mode (-gon gcc,clang) with not optimizations (-O0on gcc,clang) and run you program using valgrind
– Gabriel Devillers
Nov 14 '18 at 18:10
You should start by enabling compiler warnings (-Wall -Wextra -Wpedanticon gcc or clang, also set the compiler to optimize-O3). If you can, enable-fsanitize=addressand other sanitizers, once the code compiles without warnings.
– EOF
Nov 14 '18 at 18:26
there is no memory allocation. I do not quite know why, if it's malloc.
– Sheepp
Nov 14 '18 at 18:37
@Sheepp How do you know there is no memory allocation?
– EOF
Nov 14 '18 at 18:49
@EOF From valgrind. There is an information about 0 allocs and 0 frees.
– Sheepp
Nov 14 '18 at 18:52
You should try to compile in debug mode (
-g on gcc,clang) with not optimizations (-O0 on gcc,clang) and run you program using valgrind– Gabriel Devillers
Nov 14 '18 at 18:10
You should try to compile in debug mode (
-g on gcc,clang) with not optimizations (-O0 on gcc,clang) and run you program using valgrind– Gabriel Devillers
Nov 14 '18 at 18:10
You should start by enabling compiler warnings (
-Wall -Wextra -Wpedantic on gcc or clang, also set the compiler to optimize -O3). If you can, enable -fsanitize=address and other sanitizers, once the code compiles without warnings.– EOF
Nov 14 '18 at 18:26
You should start by enabling compiler warnings (
-Wall -Wextra -Wpedantic on gcc or clang, also set the compiler to optimize -O3). If you can, enable -fsanitize=address and other sanitizers, once the code compiles without warnings.– EOF
Nov 14 '18 at 18:26
there is no memory allocation. I do not quite know why, if it's malloc.
– Sheepp
Nov 14 '18 at 18:37
there is no memory allocation. I do not quite know why, if it's malloc.
– Sheepp
Nov 14 '18 at 18:37
@Sheepp How do you know there is no memory allocation?
– EOF
Nov 14 '18 at 18:49
@Sheepp How do you know there is no memory allocation?
– EOF
Nov 14 '18 at 18:49
@EOF From valgrind. There is an information about 0 allocs and 0 frees.
– Sheepp
Nov 14 '18 at 18:52
@EOF From valgrind. There is an information about 0 allocs and 0 frees.
– Sheepp
Nov 14 '18 at 18:52
|
show 3 more comments
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You should try to compile in debug mode (
-gon gcc,clang) with not optimizations (-O0on gcc,clang) and run you program using valgrind– Gabriel Devillers
Nov 14 '18 at 18:10
You should start by enabling compiler warnings (
-Wall -Wextra -Wpedanticon gcc or clang, also set the compiler to optimize-O3). If you can, enable-fsanitize=addressand other sanitizers, once the code compiles without warnings.– EOF
Nov 14 '18 at 18:26
there is no memory allocation. I do not quite know why, if it's malloc.
– Sheepp
Nov 14 '18 at 18:37
@Sheepp How do you know there is no memory allocation?
– EOF
Nov 14 '18 at 18:49
@EOF From valgrind. There is an information about 0 allocs and 0 frees.
– Sheepp
Nov 14 '18 at 18:52