I am running the code example for sqlite from here to create a table in C , here is the code:

#include "../contrib/sqlite/sqlite3.h"

static int callback(void* NotUsed, int argc, char** argv, char** azColName) {
    int i;
    for (i = 0; i < argc; i  ) {
        printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
    }
    printf("\n");
    return 0;
}

int main(int argc, char* argv[]) {
    sqlite3* db;
    char* zErrMsg = 0;
    int rc;
    char* sql;

    /* Open database */
    rc = sqlite3_open("test.db", &db);

    if (rc) {
        fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
        return(0);
    }
    else {
        fprintf(stdout, "Opened database successfully\n");
    }

    /* Create SQL statement */
    sql = "CREATE TABLE COMPANY("  \ // Error is here at the '='
        "ID INT PRIMARY KEY     NOT NULL," \
        "NAME           TEXT    NOT NULL," \
        "AGE            INT     NOT NULL," \
        "ADDRESS        CHAR(50)," \
        "SALARY         REAL );";

    /* Execute SQL statement */
    rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);

    if (rc != SQLITE_OK) {
        fprintf(stderr, "SQL error: %s\n", zErrMsg);
        sqlite3_free(zErrMsg);
    }
    else {
        fprintf(stdout, "Table created successfully\n");
    }
    sqlite3_close(db);
    return 0;
}

But then I get some errors from visual studio 2022 that say:

a value of type "const char *" cannot be assigned to an entity of type "char *"

'=': cannot convert from 'const char [164]' to 'char *'

Does anyone know how to fix this error?

CodePudding user response：

The problem is your sql variable. It is a char* pointer, which is a pointer to non-const character data. But you are trying to assign it to point at a string literal, which is const character data (in this case a const char[164] array). Assigning a non-const character pointer to point at const character data is dangerous, as it allows read-only strings to be mutatable, which is undefined behavior. In C (which the example you are looking at was written for) and old versions of C , such an assignment is legal (albeit not recommended), but in C 11 onward it is illegal.

You need to change the declaration of sql to const char* instead (which is what sqlite3_exec() is expecting anyway).