read_write_x64integer_text_bin, C (clang)

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//clang 3.8.0

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

//function to dump hex from file.
void hexdump(const char *const filename)
{
    FILE         *file;
    unsigned char byte;

file = fopen(filename, "rb");
    if (file == NULL)
        return;
    fprintf(stdout, "hexdump of `%s': ", filename);
    while (fread(&byte, 1, 1, file) == 1)
        fprintf(stdout, "0x%02x ", byte);
    fprintf(stdout, "\n");
}

int main(void) {
	//x64
	//write text, write binary,
	//read text, read binary
    
	FILE *fout, *filein;
	char *filename_txt = "myfile.txt";	//text filename
	char *filename_bin = "myfile.bin";	//bin filename
	
    //unsigned long long my64 = 0x1234567887654321;
	//two x64 numbers
	uint64_t my64 = 258;						//258 (dec) = 102(hex) =  0000 0000 0000 0102 -> 0201 0000 0000 0000 -> 2010000000000000 -> to file
	uint64_t my642 = 1234567891011121314;		//1234567891011121314(dec) = 112210F4B2D230A2 (hex) = 1122 10F4 B2D2 30A2 -> A230 D2B2 F410 2211 -> A230D2B2F4102211 -> to file

// write as text
    fout = fopen(filename_txt, "wt");
    fprintf(fout, "%" PRIu64 "\n", my64);
	fprintf(fout, "%" PRIu64 "\n", my642);
    fclose(fout);

// write as bytes
    fout = fopen(filename_bin, "wb");
    fwrite(&my64, sizeof(my64), 1, fout);
	fwrite(&my642, sizeof(my64), 1, fout);
    fclose(fout);    
	
    // read as text
    filein = fopen(filename_txt, "rt");
	if(filein==NULL){printf("Cann't open file \"myfile.txt\" for reading...\n");}
	else{
		printf("Try to reading file as text\n");
		char buf[1000];
		while (fgets(buf,1000,filein)!=NULL)
        	printf("%s",buf);
		fclose(filein);
	}
	
    
	// read as bytes
		/* check that the content of the file is not printable, i.e. not text */
		hexdump(filename_bin);

filein = fopen(filename_bin, "rb");
    if (filein == NULL){
		printf("Cann't open file \"myfile.bin\" for reading...\n");
        return -1;
	}
	else{
	    uint64_t value;
		printf("Try to reading file as bytes\n");
		value = 0;
		
		while(fread(&value, sizeof(value), 1, filein) == 1){
			fprintf(stdout, "The value read was %" PRIu64 "\n", value);
		}
		
		fclose(filein);
	}

system("pause");
    return 0;
}

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Compilation time: 0.24 sec, absolute running time: 0.11 sec, cpu time: 0.05 sec, memory peak: 3 Mb, absolute service time: 0,36 sec