I can’t use strcmp in C

Question

I need to show a student’s chart using the license plate, as I do?

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

main() {

  struct ficha {
    char matricula[9], inf[9];
    char nome[50];
    char curso[20];
    char periodo[10];
  };
  struct ficha alunos[2];

  int i;

  for (i = 0; i < 2; i++) {
    printf("\nInforme a matricula do aluno: ");
    scanf("%s", & alunos[i].matricula);

    printf("\nInforme o nome do aluno: ");
    scanf("%s", & alunos[i].nome);

    printf("\nInforme o curso do aluno: ");
    scanf("%s", & alunos[i].curso);

    printf("\nInforme o periodo do aluno: ");
    scanf("%s", & alunos[i].periodo);
  }

  printf("\n\nDigite uma das matriculas para informacoes de um aluno:");
  scanf("%s", & alunos[i].inf);

  if (strcmp(alunos[i].matricula, alunos[i].inf) == 0) {
    printf("\n\n---------------------------Informacoes---------------------------\n\n");

    printf("\nMatricula: %s \n", alunos[i].matricula);
    printf("\nNome: %s \n", alunos[i].nome);
    printf("\nCurso: %s \n", alunos[i].curso);
    printf("\nPeriodo: %s \n", alunos[i].periodo);

  } else
    printf("Aluno nao encontrado");
  system("pause");
}

Answer 1

As I put in the comment, you’re using scanf("%s", & alunos[i].inf); outside the for, that is, will read a value in "i" with the last value of for and that comparison won’t work.

The searched value can be a separate variable, which does not need to be in the struct since you won’t read inside the for, so for example:

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

main() {

  struct ficha {
    char matricula[9];
    char nome[50];
    char curso[20];
    char periodo[10];
  };
  
  struct ficha alunos[2];
  
  char pesquisa[9];
  bool achou = false;

  int i;

  for (i = 0; i < 2; i++) {
    printf("\nInforme a matricula do aluno: ");
    scanf("%s", & alunos[i].matricula);

    printf("\nInforme o nome do aluno: ");
    scanf("%s", & alunos[i].nome);

    printf("\nInforme o curso do aluno: ");
    scanf("%s", & alunos[i].curso);

    printf("\nInforme o periodo do aluno: ");
    scanf("%s", & alunos[i].periodo);
  }

  printf("\n\nDigite uma das matriculas para informacoes de um aluno:");
  scanf("%s", & pesquisa);

  for (i = 0; i < 2; i++) {
    if (strcmp(alunos[i].matricula, pesquisa) == 0) {
        printf("\n\n---------------------------Informacoes---------------------------\n\n");

        printf("\nMatricula: %s \n", alunos[i].matricula);
        printf("\nNome: %s \n", alunos[i].nome);
        printf("\nCurso: %s \n", alunos[i].curso);
        printf("\nPeriodo: %s \n", alunos[i].periodo);
        achou = true;
    }
  }
  
  if (achou == false) {
       printf("\nAluno nao encontrado");
  }

  system("pause");
}

Note that, after reading the value, the strcmp is inside a for to compare with each value that was entered, until finding. In case you don’t find it, I created the variable "found" that will have the initial value "false" and will change to "true" if you find.

At the end has the parole if (achou == false) to display the message if not found, which could also be if (!achou)