putting values into array-newbie doubt

[oswald.harry]

hi
i am trying to read from cmd line some strings and put them into an
array of char* ,i want to use this array lateron so i wrote

int main(int argc,char* argv[]) {
int i=0;
int totalnames=argc-1;
char* names=malloc(sizeof(char*)* totalnames);

printf("totalnames:%d\n",totalnames);
for (i=0;i<totalnames;i++){
printf("name:%d=%s\n",i+1,argv[i+1]);
names=argv[i+1];
printf("names[%d]is %s\n",i,names);

}

}

i get stackdump at the second printf in the for loop..can someone help
out?
thanx
oharry

 

[vippstar]

hi
i am trying to read from cmd line some strings and put them into an
array of char* ,i want to use this array lateron so i wrote

int main(int argc,char* argv[]) {
int i=0;
int totalnames=argc-1;
char* names=malloc(sizeof(char*)* totalnames);

Your calculations are wrong, you either want a sizeof(char) or a char
** names.
In the first case you don't need it because sizeof(char) == 1.
Also, you don't check the return value of malloc.

 

[santosh]

hi
i am trying to read from cmd line some strings and put them into an
array of char* ,i want to use this array lateron so i wrote

int main(int argc,char* argv[]) {
int i=0;
int totalnames=argc-1;

The argument 'argc' can be zero or more. If it is one it is almost
always the program's name that is in argv[argc-1].

char* names=malloc(sizeof(char*)* totalnames);

This is probably wrong. What you might want is:

char **names = malloc( totalnames * sizeof *names );
if (!names) { handle_error(); }
else {
for (i = 0; i < totalnames; i++) {
names = malloc( strlen(argv[i+1] + 1) * sizeof **names );
if (!names) { handle_error(); }
}
}
printf("totalnames: %d\n", totalnames);
for (i = 0; i < totalnames; i++) strcpy(names, argv[i+1]);
for (i = 0; i < totalnames; i++) {
printf("name: %d = %s\n", i+1, names);
}

/* free memory before exit */

printf("totalnames:%d\n",totalnames);
for (i=0;i<totalnames;i++){
printf("name:%d=%s\n",i+1,argv[i+1]);
names=argv[i+1];
printf("names[%d]is %s\n",i,names);

}

}

i get stackdump at the second printf in the for loop..can someone help
out?
thanx
oharry

 

[Walter Roberson]

The argument 'argc' can be zero or more. If it is one it is almost
always the program's name that is in argv[argc-1].

Except when it isn't. And "program's name" might mean
the filename (no path) and extension or it might mean the base filename
(no path and no extension), or it might mean the entire path
to the executable as entered by the user or program that created
the call, or it might mean the fully resolved path to the executable
(possibly after following all symbolic links). And it is not
uncommon for daemons to be launched with the argv[0] set to
some human readable phrase instead of to a program name; for example,
netscape 4 spun off a process whose argv[0] was '(dns helper)'

 

[Leonardo Korndorfer]

int main(int argc,char* argv[]) {
int i=0;
int totalnames=argc-1;
char* names=malloc(sizeof(char*)* totalnames);

If you say you want to put in an array of char* thats different than
char*
You see, char* foo[] is an array of char*, but char* names=... is not.

printf("totalnames:%d\n",totalnames);
for (i=0;i<totalnames;i++){
printf("name:%d=%s\n",i+1,argv[i+1]);
names=argv[i+1];

Why don't start i with 1? then you don't need to argv[i+1]...

printf("names[%d]is %s\n",i,names);

}

}

i get stackdump at the second printf in the for loop..can someone help
out?
thanx
oharry

 

[oswald.harry]

thanx santhosh..now i realise my mistake..
oharry

 

[h03Ein]

hi
i am trying to read from cmd line some strings and put them into an
array of char* ,i want to use this array lateron so i wrote

int main(int argc,char* argv[]) {
int i=0;
int totalnames=argc-1;
char* names=malloc(sizeof(char*)* totalnames);

printf("totalnames:%d\n",totalnames);
for (i=0;i<totalnames;i++){
printf("name:%d=%s\n",i+1,argv[i+1]);
names=argv[i+1];
printf("names[%d]is %s\n",i,names);

}

}

i get stackdump at the second printf in the for loop..can someone help
out?
thanx
oharry

the line

char* names=malloc(sizeof(char*)* totalnames);

indicates that names is pointer to characters(in other words array of
chars) not array of array of chars so your definition should be like
this :

char **names=(char **)malloc(sizeof(char*)* totalnames);

and a soultion for this problem may look like:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int main(int argc,char* argv[]) {
int i=0;
int totalnames=argc-1;
char **names=(char **)malloc(sizeof(char*)* totalnames);


printf("totalnames:%d\n",totalnames);
for (i=0;i<totalnames;i++){
printf("name:%d=%s\n",i+1,argv[i+1]);
names=argv[i+1];
printf("names[%d]is %s\n",i,names);


}

}

 

[Ian Collins]

the line

char* names=malloc(sizeof(char*)* totalnames);

indicates that names is pointer to characters(in other words array of
chars) not array of array of chars so your definition should be like
this :

char **names=(char **)malloc(sizeof(char*)* totalnames);

Forget the cast, the idiomatic form is

char **names = malloc( totalnames * sizeof *names );