What is wrong with that easy program ?

[dekl]

Hello,

I would like to know where is my mistake on that program I made :

 #include <stdio.h>

int main (int argc, char*argv[]) {

    if (argc > 1) {
        printf ("there are %d elements",argc); 
        printf ("the first element is %c",argv[1]);}
    else 
        if {printf("there is one element");}
FILE*f1;
f1 = fopen(argv[1], "w");
fprintf(f1,"%c",argv[2]);
fclose(f1);
return 0;}

when I try to compile it it says :

test.c:7:3: warning: format ‘%c’ expects argument of type ‘int’, but argument 2 has type ‘char *’ [-Wformat]
test.c:12:1: warning: format ‘%c’ expects argument of type ‘int’, but argument 3 has type ‘char *’ [-Wformat]

[stahta01]

Oop, my prior links were not the warning your were getting

read dmh2000 answer below.

Tim S.

[dmh2000]

argv[n] is a char *, not a char. if you want to print the whole argument, use argv[n] and %s. if you want to print only the first character of the argument, use argv[n][0] and %c

[dekl]

oh right I am stupid... thanks a lot

[dekl]

Thank you, this tutorial will still be usefull. (stahta01)

[dekl]

%s , s if for string right ?

[laserlight]

Yes.

[dekl]

Well so I tryed to modify my program so that I create a file with all of the arguments and not only the first one, and once again it doesn't work. can you help me again pease ?

#include <stdio.h>

int main (int argc, char*argv[]) {
int i=0;
    if (argc > 1) {
        printf ("there are %d elements",argc); 
        printf ("the first element is %s",argv[1]);}
    else 
        {printf("there is one element");}
FILE*f1;
f1 = fopen(argv[1], "w+");
for (i=1;i<=argc;i++){
fprintf(f1,"%s",argv[i]);
fclose(f1);}
return 0;}

[laserlight]

What is your current code?

[dekl]

sorry I modified my post.

[dekl]

oh I think I know

[dekl]

So I changed it to that :

#include <stdio.h>

int main (int argc, char*argv[]) {
int i=0;
    if (argc > 1) {
        printf ("there are %d elements",argc); 
        printf ("the first element is %s",argv[1]);}
    else 
        {printf("there is one element");}
FILE*f1;
f1 = fopen(argv[1], "w+");
for (i=1;i<=argc;i++){
fprintf(f1,"%s",argv[i]);}
fclose(f1);
return 0;}

now I have a segmentation falt

[laserlight]

For starters, you need to indent your code:

#include <stdio.h>
 
int main(int argc, char *argv[]) {
    int i = 0;
    if (argc > 1) {
        printf("there are %d elements", argc);
        printf("the first element is %s", argv[1]);
    } else {
        printf("there is one element");
    }
    FILE *f1;
    f1 = fopen(argv[1], "w+");
    for (i = 1; i <= argc; i++) {
        fprintf(f1,"%s", argv[i]);
        fclose(f1);
    }
    return 0;
}

Now it becomes obvious that you are calling fclose prematurely.

[dekl]

#include <stdio.h>

  
int main(int argc, char *argv[]) {
    int i = 0;
    if (argc > 1) {
        printf("there are %d elements", argc);
        printf("the first element is %s", argv[1]);
    } else {
        printf("there is one element");
    }
    FILE *f1;
    f1 = fopen(argv[1], "w+");
    for (i = 1; i <= argc; i++) {
        fprintf(f1,"%s", argv[i]);
        }
    fclose(f1);
    
    return 0;
}

thanks, I need to work on that. Now this has a segmentation falt.

[claudiu]

argv[argc] does not exist, yet you are printing it at the end of your loop.