encripting a string

[j_spinto]

int main() {
    char* string;
    FILE *fp;
    int i;
    int i2=0;
    printf("Insira o texto a codificar: ");
    scanf("%s",&string);
    while(string[i2]!='\n') {
            i2++;
    }
    string[i2]='\0';
    printf("\n");
    unsigned short int final[sizeof(string)];
    char key=(char)rand()%256;
    for(i=0; string[i]!='\0';i++) {
            final[i]=((int)string[i]*((int)key+1));
    }
    fp=fopen("keylog","a+");
    fputc(fp,(int)key);
    fclose(fp);
    printf("%hu\n",final);
    system("pause");
    return 0;
}

please say me whats wrong... i dont understand! :S

[itsme86]

What does it do or not do that you were or weren't expecting it to do?

[j_spinto]

it gives me an error and asks me to send an error report to microsoft after entering the string lol

the compiler warnings are those (theyre quite stupid, because the syntax is differente from the cppreference.com of the functions i use):
in function `main'
[warning] passing arg 1 of `fputc' makes integer from pointer without a cast
[warning] passing arg 2 of `fputc' makes pointer from integer without a cast

[nkhambal]

Your variable string is a pointer to char. It is not pointing anywhere (not even to NULL). You have not allocated any memory to it using malloc() or calloc(). This why, when you are trying to write into it. (or dereference it) using scanf(), its crashing the program after you enter the string. Your string pointer is trying to perform an illegal operation by trying to write into some one else's memory region. malloc() string first before using it in scanf().

And yes, you dont need to use & operator when you are using string variable in scanf() since its a pointer.

[quzah]

1) Try actually including the header files you're supposed to include.
2) You have the arguments backwards. Read this.

The warnings aren't "stupid", they're correct.


Quzah.

[j_spinto]

#include <stdlib.h>
#include <stdio.h>

int main() {
    char string[BUFSIZ];
    FILE *fp;
    int i;
    int i2=0;
    printf("Insira o texto a codificar: ");
    scanf("%s",&string);
    while(string[i2]!='\n') {
            i2++;
    }
    string[i2]='\0';
    printf("\n");
    unsigned short int final[sizeof(string)];
    char key=(char)rand()%256;
    for(i=0; string[i]!='\0';i++) {
            final[i]=((int)string[i]*((int)key+1));
    }
    fp=fopen("keylog","a+");
    fputc(fp,(int)key);
    fclose(fp);
    printf("%hu\n",final);
    system("pause");
    return 0;
}

what's the matter now ? (i had already included the files but i didnt paste them)

[j_spinto]

ups, i see.. i corrected the arguments but it ddoesnt work !

[caduardo21]

This will at least compile...

#include <stdlib.h>
#include <stdio.h>

int main() {
    char string[BUFSIZ];
    FILE *fp;
    int i;
    int i2=0;
    printf("Insira o texto a codificar: ");
    scanf("%s",&string);
    while(string[i2]!='\n') {
            i2++;
    }
    string[i2]='\0';
    printf("\n");
    unsigned short int final[sizeof(string)];
    char key=(char)rand()%256;
    for(i=0; string[i]!='\0';i++) {
            final[i]=((int)string[i]*((int)key+1));
    }
    fp=fopen("keylog","a+");
    fputc((int)key, fp);
    fclose(fp);
    printf("%hu\n",final);
    system("pause");
    return 0;
}

Now see if it's doing what you want to do.

EDIT:
One more thing: you don't need the & operator when passing a pointer to an array of characters to scanf().

[j_spinto]

still gives me an error