How to call store procedure in pro c

Usually, you call a stored procedure something like this :

EXEC SQL EXECUTE
BEGIN
    :retval := package1.procedure2(:p1, :p2, :p3, :p4, :p5);
END;
EXEC-SQL;

check this http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14407/pc_07pls.htm#g27962

I did that but now get warnings :
char     retval [100];
EXEC SQL EXECUTE
BEGIN
    :retval := package1.procedure2(:p1, :p2, :p3, :p4, :p5);
END;
END-EXEC;


"prog.c", line 1502.11: 1506-280 (W) Function argument assignment between types "char*" and "char" is not allowed.
"prog.c", line 1503.11: 1506-280 (W) Function argument assignment between types "char*" and "char" is not allowed.
"prog.c", line 1504.11: 1506-280 (W) Function argument assignment between types "char*" and "char" is not allowed.
"prog.c", line 1505.11: 1506-280 (W) Function argument assignment between types "char*" and "char" is not allowed.
"prog.c", line 1506.11: 1506-280 (W) Function argument assignment between types "char*" and "char" is not allowed.

what's the definition of the stored procedure, and how are p1 through p5 defined ?

it's a function
FUNCTION abcd(
      p1              IN        VARCHAR2,
      p2              IN        VARCHAR2,
      p3              IN        VARCHAR2,
      p4              IN        VARCHAR2,
      p5              IN        VARCHAR2
   ) RETURN VARCHAR2 IS

 in pro c they as:
 char     p1;
  char     p2;
  char     p3;
  char     p4;
  char     p5;

You defined p1 through p5 as chars, and they need to be strings. Define them as VARCHAR2's in a SQL DECLARE block.

I was not able to define as VARCHAR2 but define them VARCHAR but got errors

>> but got errors

What errors ? And what's your code now ?

EXEC SQL BEGIN DECLARE SECTION;
  VARCHAR  sqlstmt[400];
  int      cid;
  VARCHAR  cName[100];
  VARCHAR b1[100];
  VARCHAR b2[100];
  VARCHAR b3[100];
  VARCHAR b4[100];
  VARCHAR b5[100];
  EXEC SQL END DECLARE SECTION;

  tData    Data; /* is a structuer*/

 (GetName(&Data.techId, &Data.Name));

  strncpy(b1,Data.Name.B1,8);
  strncpy(b2,Data.Name.B2,8);
  strncpy(b3,Data.Name.B3,8);
  strncpy(b4,Data.Name.B4,8);
  strncpy(b5,Data.Name.B5,8);

   EXEC SQL EXECUTE
   BEGIN
     :cName := package.procedure(:b1
                                         ,:b2
                                         ,:b3
                                         ,:b4
                                         ,:b5);
   END;
   END-EXEC;


"user.c", line 1517.11: 1506-280 (S) Function argument assignment between types "char*" and "struct {...}" is not allowed.
"user.c", line 1518.11: 1506-280 (S) Function argument assignment between types "char*" and "struct {...}" is not allowed.
"user.c", line 1519.11: 1506-280 (S) Function argument assignment between types "char*" and "struct {...}" is not allowed.
"user.c", line 1520.11: 1506-280 (S) Function argument assignment between types "char*" and "struct {...}" is not allowed.
"user.c", line 1521.11: 1506-280 (S) Function argument assignment between types "char*" and "struct {...}" is not allowed.

Now, I am getting below if I chnage them char[]

"user.c", line 1495.9: 1506-131 (S) Explicit dimension specification or initializer required for an auto or static array.
"user.c", line 1496.9: 1506-131 (S) Explicit dimension specification or initializer required for an auto or static array.
"user.c", line 1497.9: 1506-131 (S) Explicit dimension specification or initializer required for an auto or static array.
"user.c", line 1498.9: 1506-131 (S) Explicit dimension specification or initializer required for an auto or static array.
"user.c", line 1499.9: 1506-131 (S) Explicit dimension specification or initializer required for an auto or static array.
"user.c", line 1500.9: 1506-131 (S) Explicit dimension specification or initializer required for an auto or static array.

Well, you need to specify the length of the char array ...