How to save the content of a structure to a file in C?

Question

I have a given structure. I read all the characters of a txt-file and save it to a multidimensional array (lines) that i defined within the struct. Then I want to hand the struct variable over to a function which should then print all the characters to another txt-file.

Thats what I have:

typedef struct _content {
    int length;
    char **lines;    // multidimensional array
} content_t;


int curline = 0;     //global variables
int curchar = 0;

...

struct _content inhalt;
c = fgetc(ptr);

...

void write_content(char *filename, content_t *content)
{
    FILE *pFile;
    pFile = fopen(filename, "a");

    printf("\nWriting Char Nr. %d in line: %d", curchar, curline);

    fputc(content->lines[curline][curchar], pFile);

    printf("\nJust wrote char Nr. %d in line: %d !", curchar, curline);

}

...

    while(c != EOF)     
    {
        inhalt.lines[curline][curchar] = c;

        //where I call the function write_content:
        write_content("write-file.txt", &inhalt);

        if(c == '\n')      
        {
            inhalt.length++;      
            curline++;      
            inhalt.lines[curline] = malloc(255);
            curchar = 0;
        }
        else
        {
        curchar++;
        }
        c = fgetc(ptr);     
        printf("%c", c);    

    } 

The last output is: "just wrote char Nr. 36 in line: 22"

But the last char written into the file is Nr 0 in line 10...

Answer 1

You are using a pointer to your struct so you need to use fputc(content->lines[curline][curchar], pFile).

Btw: If your lines are null-terminated you can use fputs(content->lines[curline], pFile)

Also @Someprogrammerdude is right you should define write_content prior to calling it.

Refering to the comments:

void write_content(char *filename, content_t *content)
{
    FILE *pFile;
    pFile = fopen(filename, "a");

    for(int line = 0; line <= curline; line++){
        for(int c = 0; content->lines[line][c] != 0; c++){ // because 0 terminates the string
            printf("\nWriting Char Nr. %d in line: %d", c, line);
            fputc(content->lines[line][c], pFile);
        }
    }
    fclose(pFile);

}
// ...

while(c != EOF){
    inhalt.lines[curline][curchar] = c;

    if (c == '\n')      
    {
        inhalt.lines[curline][curchar+1] = 0; // ensure null termination
        inhalt.length++;      
        curline++;      
        inhalt.lines[curline] = malloc(255);
        curchar = 0;
    }
    else
    {
        curchar++;
    }
    c = fgetc(ptr);     
    printf("%c", c);    
} 
//where I call the function write_content:
write_content("write-file.txt", &inhalt);