When using gets to get a file name in C, the file

问题:

I'm trying, in C, to get a string from user input so the program can open a chosen file.
I tried using fgets because I read on numerous threads that it is the safer option (as opposed to gets).
However when a string is stored using gets, the file opens, but with fgets it does not.

Here is the code I'm using:

char csvFile[256];
FILE *inpfile;

printf("Please enter CSV filename: ");
fgets(csvFile,256,stdin);

printf("\nFile is %s\n",csvFile);

inpfile = fopen(csvFile,"r");

if(inpfile == NULL)
{
    printf("File cannot be opened!");
}

I know the file exists but with fgets the if block is entered.
The only difference is that using:

gets(csvFile);

works in place of

fgets(csvFile,256,stdin);

Can anyone help me make sense of this? Thanks in advance.

回答1:

You need to remove the trailing newline:

char csvFile[256], *p;

fgets(csvFile, sizeof csvFile, stdin);
if ((p = strchr(csvFile, '\n')) != NULL) { 
    *p = '\0'; /* remove newline */
}

回答2:

You can check the newline character at the end of csvFile by adding for example two "=" at the first and end of your sentence, respectively.

printf("\n=File is %s=\n",csvFile);

You can easily remove the newline character at the end of csvFile using strtok() function from <string.h> library. So you may need to add one line of code after reading the input string with fgets() in the following manner:

fgets(csvFile, sizeof csvFile, stdin);
strtok(csvFile, "\n");

回答3:

The difference you observed between fgets and gets is that fgets leaves the newline character at the end of the read string. But it should not cause you to going back to gets - just remove the last character in csvFile if it is newline.