error: expected expression before ‘char’

Question

Excuse me , I have a problem when I compile my code, and i don't don't how to solve it because I don't know what it ask for.

This appears me in the terminal:

" usr/lib/gcc/x86_64-linux-gnu/4.9/../../../x86_64-linux-gnu/crt1.o: In the functión _start': /build/buildd/glibc-2.21/csu/../sysdeps/x86_64/start.S:114: reference tomain' without define collect2: error: ld returned 1 exit status "

I leave my code:

#include<stdio.h>
#include<string.h>
void calcular_vocal(char cadena[]){
   int l;
   char vocales[5]="a,e,i,o,u";
   int i, vector contadores[5];
   l=strlen(cadena);
   for(i=0;i<l;i++){
     if(cadena[i] =='a')
        cadena a++;
        vector contadores[0]++;
     if(cadena[i] =='e')
        cadena e++;
        vector contadores[1]++;;
     if(cadena[i] == 'i')
        cadena i++;
        vector contadores[2]++;
     if(cadena[i] =='o')
        cadena o++;
        vector contadores[3]++;
     if(cadena[i] =='u')
        cadena u++;
        vector contadores[4]++;
    for(i=0;i<5;i++){
      int max,pos;
      if(vector contadores[i]>max){
         max = vector contadores [i];
         pos = i;
      }
    }
     printf("The most repeated vocal is %c %d",vocales[pos],max);
   }
}
int main (void){
   char calcular_vocal(char[]);
}

Answer 1

Update

It seems you are compiling the wrong file. See the following console commands and output (its german, but I think the message is sufficiently similar to yours):

$ rm test1.c 
$ touch test1.c
$ gcc test1.c 
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In Funktion `_start':
(.text+0x20): Nicht definierter Verweis auf `main'
collect2: error: ld returned 1 exit status
$ 

Long story short: you compile the wrong file (probably an empty one) and for that reason you get this error message which is totally unrelated to any of your code.

---

Original Answer

I'm going to assume a few things about your code, in order to provide you an answer that results in a compilable code - whether the result of running the program means anything is up to you (to be honest, I intentionally suggest changes that won't give you the program you most probably want, since you need something to learn with).

I start with your main function

int main (void){
   char calcular_vocal(char[]);
}

What you do inside the main function, is writing a declaration of the calcular_vocal function, but with a different function signature than your actual implementation. Change it to void calcular_vocal(char[]); in order to have this part compilable.

Now to the code inside the calcular_vocal function:

The line char vocales[5]="a,e,i,o,u"; is not allowed, because the string size is to big for your array. Increase the array size to 9 or 10 in order to have enough space available: char vocales[9] = "a,e,i,o,u";

Moving on to line int i, vector contadores[5];, assuming you want to have a variable named "vector contadores". You cannot have space in your variable names, so rename it to "vector_contadores" for all occurences in order to make this piece work.

Moving on to all the if-statements. They are all the same, so I only write something about the first one. The code cadena a++; is invalid. You have multiple options to solve this. (1) erase the a from that code (cadena++;). (2) define integer variable for a and remove cadena from the code (a++;). (3) rewrite to cadena['a']++;. There are even more options to make this part compileable.

The variables int max,pos; are defined inside the for-loop but are used outside. Move their definition to the top of the function, where you define your other variables. Also, initialize max with value -1.

This should be all you need to compile this piece of code (unless I forgot something)