Compilare: user.c: In function ‘main’: user.c:19:15: warning: implicit declaration of function ‘strlen’ [-Wimplicit-function-declaration] int n=strlen(s); ^~~~~~ user.c:19:15: warning: incompatible implicit declaration of built-in function ‘strlen’ user.c:19:15: note: include ‘<string.h>’ or provide a declaration of ‘strlen’ user.c:53:9: warning: implicit declaration of function ‘strcpy’ [-Wimplicit-function-declaration] strcpy(nou,""); ^~~~~~ user.c:53:9: warning: incompatible implicit declaration of built-in function ‘strcpy’ user.c:53:9: note: include ‘<string.h>’ or provide a declaration of ‘strcpy’ user.c:13:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&t); ^~~~~~~~~~~~~~~~~ user.c:15:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%c",&c); ^~~~~~~~~~~~~~~~~ user.c:18:9: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Wunused-result] fgets(s,1000000,f); ^~~~~~~~~~~~~~~~~~