CODEWITHSUNDEEP
cstringparameters
jungrylls
jungrylls

Reputation: 29

Passing a string as an argument to a function, then use that string value to open a file In C

Suppose I have two methods: int main(void) and void func(char *FileName).

The main method will scan in, the name of a file from a user then save the value to char fileInput[20], then call func(fileInput).

In the func method, I want to open a file FILE *infile = fopen(/*FileName as string value*/, "rb");, but using the parameter value as the file name to be opened.

void func(char *FileName){
    //Open the file.        
    //FileName = address of first element of char array
    //*FileName = value of first element of char array
    //But How can I use the all the elements of the char array as a string ?
    FILE *infile = fopen(/*FileName as string value*/, "rb"); 
}

int main(void) {
    //Assuming the user will always enter a valid value.
    char fileInput[20];
    //Prompt the user to input a value.
    printf("File name then enter: ");
    //Save the input value to fileInput.
    scanf("%s", fileInput);
    func(fileInput);
}

As an example, if the fileInput[20] = "hello";, then call the func(fileInput);

How can i open a file in the func method using the "hello" value?

FILE *infile = fopen(value of fileInput = "hello", "rb");

Upvotes: 0

Views: 364

Answers (1)

alex01011
alex01011

Reputation: 1702

I am not sure if this is what you are asking but, this is the function prototytpe of fopen(),

FILE *fopen(const char *pathname, const char *mode);

pathname is a pointer to char. You are not limited to hard-coding the pathname, you can provide a variable to it (assuming its of type char *).

So this:

FILE *infile = fopen(/*FileName as string value*/, "rb");

Becomes this:

FILE *infile = fopen(FileName, "rb"); /* Filename is the argument you provided by calling the function */

Upvotes: 1

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