Question

此程序应输入一个数字并计算学生标记之间的平均值。此程序仅适用于前学生，但不适用于以下学生。我觉得fscanf有一个错误。有人可以帮忙吗？

int main ()
{
    FILE *cfPtr;
    int matricola_in, matricola, nEsami, codEsame, voto;
    char nome[20], cognome[20];
    int i, j, trovato = 0;
    float somma = 0.0;

    printf("Inserisci una matricola:\n");
    scanf("%d", &matricola_in);

    if( (cfPtr = fopen("studenti.txt", "r")) == NULL )
        printf("Errore");

    while( !feof(cfPtr) || trovato != 1 ){
        fscanf(cfPtr, "%d%s%s%d\n", &matricola, nome, cognome, &nEsami);
        if( matricola_in == matricola ){
            trovato = 1;
            for( i = 0; i < nEsami; i++ ){
                fscanf(cfPtr, "%d%d\n", &codEsame, &voto);
                somma += voto;
            }
            printf("Media: %.1f\n", somma/nEsami);
        }
    }

    fclose(cfPtr);

    return 0;
}

编辑：数据如下：

matricola nome cognome n.esami`<eol>`
(for n.esami-rows)codice esame voto`<eol>`
...

Answer 1

不清楚，但似乎该文件包含具有四个或两个项目的行的混合考虑阅读每一行。使用sscanf将该行解析为最多四个字符串。根据需要使用sscanf来捕获行中的整数。如果有两个项目，请在trovato标志表示找到匹配项时处理它们。如果有四个项目，请查看是否匹配并设置trovato。

int main ()
{
    FILE *cfPtr;
    int matricola_in, matricola, nEsami, codEsame, voto;
    char nome[20], cognome[20];
    char temp[4][20];
    char line[200];
    int result;
    int i, j, trovato = 0;
    float somma = 0.0;

    printf("Inserisci una matricola:\n");
    scanf("%d", &matricola_in);

    if( (cfPtr = fopen("studenti.txt", "r")) == NULL ) {
        printf("Errore");
        return 0;
    }

    while( fgets ( line, sizeof line, cfPtr)){//read a line until end of file
        result = sscanf ( line, "%19s%19s%19s%19s", temp[0], temp[1], temp[2], temp[3]);//scan up to four strings
        if ( result == 2) {//the line has two items
            if ( trovato) {// match was found
                sscanf ( temp[0], "%d", &codEsame);
                sscanf ( temp[1], "%d", &voto);
                somma += voto;
            }
        }
        if ( result == 4) {//the line has four items
            if ( trovato) {
                break;//there was a match so break
            }
            sscanf ( temp[0], "%d", &matricola);
            sscanf ( temp[3], "%d", &nEsami);
            if( matricola_in == matricola ){//see if there is a match
                trovato = 1;//set the flag
            }
        }
    }
    printf("Media: %.1f\n", somma/nEsami);//print results

    fclose(cfPtr);

    return 0;
}

我不确定如何正确使用fscanf

1 个答案: