[英]C coding - First number in text file not being read the way I expected
I'm doing a function that consists of reading elements of a file I wrote and priting them.我正在做一个 function ,其中包括读取我编写的文件的元素并打印它们。 The problem is, it seems the first number for every line of the text file is being read and printed in a way I don't understand on how it arrived.问题是,似乎文本文件每一行的第一个数字正在以一种我不明白它是如何到达的方式被读取和打印。 It's mostly numbers from 90-110 and zeros.它主要是 90-110 和零的数字。
I tried chaging the variable to chars and floats, but neither worked.我尝试将变量更改为字符和浮点数,但都没有奏效。
void imprimir_tabela(){
FILE *tabela = fopen("tabela.txt", "r");
if(tabela == NULL){
printf("TABELA INVALIDA OU NAO ACHADA");
printf("erro 404");
exit(404);
}
int numero_atomico;
char abreviacao;
char nome[20];
float massa_atomica;
int grupo;
int periodo;
while(!feof(tabela))
{
fscanf(tabela, "%d %s %s %f %d %d", &numero_atomico, &abreviacao, &nome, &massa_atomica, &grupo, &periodo);
printf("%d - %s - %s - Massa atomica: %0.3f - Grupo: %d - Periodo: %d\n", numero_atomico, &abreviacao, &nome, massa_atomica, grupo, periodo);
}
rewind(tabela);
return 0;
Sample lines of the text file文本文件的示例行
1 H Hidrogenio 1.008 1 1
2 He Helio 4.003 18 1
3 Li Litio 6.941 1 2
See comments in the code below请参阅下面代码中的注释
void imprimir_tabela(){
FILE *tabela = fopen("tabela.txt", "r");
if(tabela == NULL){
printf("TABELA INVALIDA OU NAO ACHADA");
printf("erro 404");
exit(404);
}
int numero_atomico;
char abreviacao;
char nome[20];
float massa_atomica;
int grupo;
int periodo;
do { // Use to be while(!feof(tabela)) - See link in the comments section
{
// 1 H Hidrogenio 1.008 1 1
// For reference
// 1. Prevent buffer over run
// 3. record return value
int ret = fscanf(tabela, "%d %c %19s %f %d %d\n", &numero_atomico, &abreviacao, &nome, &massa_atomica, &grupo, &periodo);
switch (ret) {
case 6: // Ok
printf("%d - %c - %s - Massa atomica: %0.3f - Grupo: %d - Periodo: %d\n", numero_atomico, abreviacao, &nome, massa_atomica, grupo, periodo);
break;
case EOF: // End of file - we are done
break:
default:
// Report error - take some action - in this case exit
fprintf(stderr, "Error in file %s\n", "tabela.txt");
exit(-1);
// Are we done
} while (ret != EOF);
// rewind(tabela); - Not required
// But this is
fclose(tabela);
return 0;
}
And please fix the indentation - I leave that as an exercise to the reader请修正缩进 - 我把它作为练习留给读者
At least this problem: reading into char
as if it was enough for a string .至少这个问题:读入char
就好像它对于string来说已经足够了。
char abreviacao;
// vv --- needs more meory than 1 `char`
fscanf(tabela, "%d %s %s %f %d %d",
&numero_atomico, &abreviacao, &nome, &massa_atomica, &grupo, &periodo);
Same problem with printf()
printf()
有同样的问题
Also还
Limit input width of string限制字符串的输入宽度
check the return value of scanf()
.检查scanf()
的返回值。
int numero_atomico;
//char abreviacao;
char abreviacao[4]; // Some elements need 3 letters.
char nome[20];
float massa_atomica;
int grupo;
int periodo;
// while(!feof(tabela))
while(fscanf(tabela, "%d %3s %19s %f %d %d",
&numero_atomico, abreviacao, nome, &massa_atomica, &grupo, &periodo) == 6) {
printf("%d - %s - %s - Massa atomica: %0.3f - Grupo: %d - Periodo: %d\n",
numero_atomico, &abreviacao, &nome, massa_atomica, grupo, periodo);
}
// rewind(tabela); // not needed
Recommend also to use double massa_atomica
.还推荐使用double massa_atomica
。
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