How to store string from an array of strings in to a variable in C

Question

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
void main()
{
 char movie[15];
 char movielist[25][30]={"thalaiva","aruvi","sarkar","visvasam","veeram","mersal","bigil","kaithi","mahanadhi","papanasam","vishwaroopam","padayappa","thadam","indian","petta","kaala","psycho","comali","bahubali","saaho","enthiran","vettai","asuraguru","penguin","cocktai"};
 movie=movielist[rand()%25];
 printf("%s",movie);

}

I want the variable movie to store any random string from the array movielist! The code above gives me error. main.c:8:7: error: assignment to expression with array type movie=movielist[rand()%25];

If you want to make a copy use strcpy not assignment as that is not how you copy a string. If you just want to reference the original string then use a char pointer (char *). — kaylum
– kaylum, Commented Aug 1, 2020 at 7:55
Also you may want to see c - srand() — why call it only once? - Stack Overflow — MikeCAT
– MikeCAT, Commented Aug 1, 2020 at 7:58
Unless you are programming in a freestanding environment (without the benefit of any OS), in a standards conforming implementation, the allowable declarations for main for are int main (void) and int main (int argc, char *argv[]) (which you will see written with the equivalent char **argv). See: C11 Standard - §5.1.2.2.1 Program startup(p1). See also: What should main() return in C and C++? — David C. Rankin
– David C. Rankin, Commented Aug 1, 2020 at 7:58
Avoid the use of the ancient DOS header conio.h, that makes your code 100% non-portable. (you don't use anything from that header in your code above) You can use getchar() to hold the terminal window open on windows, instead of getch(). — David C. Rankin
– David C. Rankin, Commented Aug 1, 2020 at 8:06

RobertS supports Monica Cellio · Accepted Answer · 2020-08-01 15:24:15Z

Your code has two main issues.

1.

With

movie = movielist[rand() % 25];

you attempt to assign movie(an array of 15 char, type char [15]) by a pointer to an array of 30 char (type char (*)[30]). This is not permissible in C. You cannot assign arrays.

Since you don't want to modify/change the movie titles/strings in the program, you don't need a two-dimensional array for movielist and an array for movie.

Use an array of pointer for movielist which point to string literals and a pointer for movie instead.

The pointer move you assign then by the value of one of the pointers in movielist.

2.

rand() needs a seed with srand(). Without that, rand() won't work properly. But you forgot that in your code.

A usual way is to provide a seed dependent upon the CPU clock time.

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <time.h>       // for the time seed.

int main (void)
{
   char const * movie;
   char const * const movielist[] = { 
                                       "thalaiva","aruvi","sarkar","visvasam","veeram",
                                       "mersal","bigil","kaithi","mahanadhi","papanasam",
                                       "vishwaroopam","padayappa","thadam","indian",
                                       "petta","kaala","psycho","comali","bahubali",
                                       "saaho","enthiran","vettai","asuraguru","penguin",
                                       "cocktai"
                                    };

   // initialize random seed.
   srand(time(NULL));

   movie = movielist[rand() % 25];

   printf("%s", movie);
}

Side note:

void main() is not compliant to the C standard. Use int main (void).

Thanx a lot for your explanation :) @RobertS supports Monica Cellio

tdao · Accepted Answer · 2020-08-01 08:00:10Z

1

Use char pointer instead of char array:

char *movie;  // instead of char movie[15];
...
movie = movielist[rand() % 25];

If you use movie[15] as you did, you can't assign it to individual item in the movielist as assignment operator does not work with array.

edited Aug 1, 2020 at 8:00

answered Aug 1, 2020 at 7:56

tdao

17.8k6 gold badges45 silver badges57 bronze badges

2 Comments

David C. Rankin Over a year ago

Note, you should use const char *movie; to make clear what movie points to is immutable. (compared to a mutable result provided by @MikeCAT)

David C. Rankin Over a year ago

Also understand using a pointer does not store a string from your array, it simply holds the address to an existing element within the array.

MikeCAT · Accepted Answer · 2020-08-01 07:56:26Z

You can use strcpy() for copying strings.

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
{
 char movie[30];
 char movielist[25][30]={"thalaiva","aruvi","sarkar","visvasam","veeram","mersal","bigil","kaithi","mahanadhi","papanasam","vishwaroopam","padayappa","thadam","indian","petta","kaala","psycho","comali","bahubali","saaho","enthiran","vettai","asuraguru","penguin","cocktai"};
 strcpy(movie,movielist[rand()%25]);
 printf("%s",movie);

}

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