binaryfiles - Read/Write int Binary File in C error -


i facing error reading/writing binary file in c. issue is: - write int (e.g. 2) file using fwrite - try read int file using fread - when read it, doesn't come out 2, rather long number e.g. 967899906 or 2071332354 or 1030372866 (always different).

i write binary file in c this:

file * writefile = fopen("test.bin","wb");  //test int vars int test1 = 1; int test2 = 2; int test3 = 3;  //writing ints binary file fwrite(&test1,1,1, writefile); fwrite(&test2,1,1, writefile); fwrite(&test3,1,1, writefile);  fclose(writefile);

i read file this:

file *readfile = fopen("test.bin","rb"); int data; while(fread(&data,1,1, readfile)==1){    printf("%d", data); //here output random number } fclose(readfile);

fwrite wants, second parameter, size of data write, in case sizeof(int)

same thing fread

#include <stdio.h>  int main(void) {      file * writefile = fopen("test.bin","wb");       if (writefile != null)      {          //test int vars          int test1 = 1;          int test2 = 2;          int test3 = 3;           //writing ints binary file          fwrite(&test1,sizeof(test1),1, writefile);          fwrite(&test2,sizeof(test2),1, writefile);          fwrite(&test3,sizeof(test3),1, writefile);           fclose(writefile);      }      else      {          perror("error opening file write: ");          return 1;      }        file *readfile = fopen("test.bin","rb");      if (readfile != null)      {          int data;          while(fread(&data,sizeof(data),1, readfile)==1){             printf("%d\n", data);          }          fclose(readfile);      }      else      {          perror("error opening file read: ");          return 1;      }      return 0; }

hint: test if fopen succeed.

edit

to use 1 byte variable, commented, use uint8_t variables

#include <stdio.h> #include <stdint.h>  int main(void) {      file * writefile = fopen("test.bin","wb");       if (writefile != null)      {          //test int vars          uint8_t test1 = 1;          uint8_t test2 = 2;          uint8_t test3 = 3;           //writing ints binary file          fwrite(&test1,sizeof(test1),1, writefile);          fwrite(&test2,sizeof(test2),1, writefile);          fwrite(&test3,sizeof(test3),1, writefile);           fclose(writefile);      }      else      {          perror("error opening file write: ");          return 1;      }        file *readfile = fopen("test.bin","rb");      if (readfile != null)      {          uint8_t data;          while(fread(&data,sizeof(data),1, readfile)==1){             printf("%d\n", data);          }          fclose(readfile);      }      else      {          perror("error opening file read: ");          return 1;      }      return 0; }

Comments

Post a Comment

Popular posts from this blog

commonjs - How to write a typescript definition file for a node module that exports a function? -

consider, toml node module can use: // toml.d.ts declare module toml { export function parse(value:string):any; } declare module "toml" { export = toml; } then: /// <reference path="../../../../../defs/toml/toml.d.ts"/> import toml = require('toml'); toml.parse(...); however, node module export single function, such 'glob' ( https://github.com/isaacs/node-glob ). the node usage of module be: var glob = require("glob") glob("*.js", {}, callback(err, files) { ... }); you'd naively expect this: // glob.d.ts declare function globs(paths:string, options:any, callback:{(err:any, files:string[]):void; ...but because typescripts 'import' semantics bit strange, seems can use 'import .. = require()' statement alias modules . trying call: /// <reference path="../../../../../defs/glob/glob.d.ts"/> import blog = require('glob'); results in: error ts2072: mod...
Read more

openid - Okta: Failed to get authorization code through API call -

i'm integrating okta own idp server using okta's api. i'm implementing authorization code flow following steps below: in own server, use /api/v1/authn endpoint sessiontoken. use sessiontoken obtain authorization calling endpoint: /oauth2/v1/authorize?client_id=" + clientid + "&sessiontoken=" + sessiontoken + "&response_type=code&response_mode=query&scope=openid&redirect_uri=" + redirecturl + "&state=evanyang&nonce=" it's supposed return response status code 302 , location header containing redirect url code value. however, keep getting response status code 200 , without location header, html body saying "you using unsupported browser." , "javascript disabled on browser." according api documentation: http://developer.okta.com/docs/api/resources/oidc.html#authentication-request , sessiontoken parameter sufficient this: an okta one-time sessiontoken. allows api-based ...
Read more

ios - Change Storyboard View using Seague -

i have following code checks connection server, , depending on want change views if no connection found. nsstring *connect = [nsstring stringwithcontentsofurl:[nsurl urlwithstring:@"http://myserver.com"] encoding:nsutf8stringencoding error:nil]; if (connect == null) { [self performseguewithidentifier:@"network_failure" sender:self]; } else { // other code here } my problem not change views. have added storyboard segue between 2 views identifier of network_failure . not have navigation controller or that, problem? thanks help! no not problem. first of all, in objectivec exists nil object oriented null . must use that. so: if(connect == nil) or better: if(!connect) so due fact nil not same of null , probably code does't enter in if scope . you have been able discover breakpoint. anyway: be sure set trigger segue (line) 2 view controller , , name network_failure (that not best name. should instead view1toview2 ) as, m...
Read more